{"gene":"CD48","run_date":"2026-06-09T22:57:18","timeline":{"discoveries":[{"year":1992,"finding":"CD48 is the ligand (counter-receptor) for mouse CD2; identified by generating a chimeric CD2-IgG fusion protein that bound to CD48 on T cell lines, confirmed by protein microsequencing of the affinity-purified antigen, reactivity with recombinant CD48, and inhibition of CD2–CD48 binding by soluble CD48. CD48 is a GPI-anchored glycoprotein (~45 kD) predominantly expressed on hematopoietic cells.","method":"Chimeric CD2-IgG fusion protein pulldown, protein microsequencing, mAb inhibition assays, soluble recombinant protein competition","journal":"The Journal of experimental medicine","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — reciprocal binding assays with soluble proteins, protein microsequencing, mAb blocking, and functional T-cell activation assays in a single study","pmids":["1383383"],"is_preprint":false},{"year":1993,"finding":"Quantitative kinetic and affinity analysis of rat CD2–CD48 interaction by surface plasmon resonance (BIAcore) revealed a very low-affinity interaction (KD ~60–90 µM) driven by an extremely rapid off-rate (koff ≥ 6 s⁻¹), with a normal on-rate (kon ≥ 10⁵ M⁻¹s⁻¹). Glycosylation of CD2 had little effect on binding affinity.","method":"Surface plasmon resonance (BIAcore) with soluble recombinant proteins in both binding orientations","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 1 / Strong — rigorous biophysical assay in both orientations with soluble proteins, replicated in complementary ultracentrifugation study (PMID:9188168)","pmids":["7903240"],"is_preprint":false},{"year":1995,"finding":"The CD2-binding site on rat CD48 lies on the GFCC'C'' beta-sheet of its membrane-distal Ig domain (equivalent to the CD2 ligand-binding surface). Complementary charged-residue mutations in CD48 and CD2 demonstrated direct electrostatic contacts between the two binding surfaces, establishing a head-to-head docking topology. The modeled CD2–CD48 complex spans ~134 Å, similar to the predicted TCR–pMHC complex distance.","method":"Complementary site-directed mutagenesis of CD48 and CD2, functional binding assays, molecular modelling","journal":"Current biology : CB","confidence":"High","confidence_rationale":"Tier 1 / Moderate — mutagenesis with complementary charge-swap pairs establishing direct contact residues, supported by modelling and later crystallographic confirmation","pmids":["7697352"],"is_preprint":false},{"year":1996,"finding":"NMR titration of ¹⁵N-labelled rat CD2 domain 1 with soluble CD48 identified the CD48-binding surface of CD2 as the GFCC'C'' face (~700–800 Ų), with no large-scale structural changes in CD2 upon CD48 binding. Species- and ligand-specific binding differences between rat and human CD2 are explained by as few as three residues (Thr37, Leu38, Glu41 in rat; Lys42, Lys43, Gln46 in human).","method":"Heteronuclear NMR (²D ¹⁵N-¹H HSQC) titration with soluble CD48","journal":"Biochemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — direct NMR mapping of binding surface with chemical shift perturbation analysis, consistent with mutagenesis data","pmids":["8634239"],"is_preprint":false},{"year":1997,"finding":"Analytical ultracentrifugation (sedimentation equilibrium and velocity) in free solution confirmed the weak affinity of the rat CD2–CD48 interaction (KD 20–110 µM at 5°C), ruling out significant self-association of either reactant as a confounding factor in SPR measurements.","method":"Analytical ultracentrifugation (sedimentation equilibrium and velocity)","journal":"European biophysics journal : EBJ","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — orthogonal biophysical method confirming SPR-derived affinity, single study","pmids":["9188168"],"is_preprint":false},{"year":1998,"finding":"2B4 (CD244) is an additional ligand for CD48: recombinant mouse 2B4 extracellular domain bound to CD48-expressing cells and this binding was blocked by anti-CD48 mAbs. Surface plasmon resonance showed mCD48 binds m2B4 with 6–9-fold higher affinity (KD ~16 µM at 37°C) than it binds CD2; human CD48 bound human 2B4 with KD ~8 µM.","method":"Fluorescent bead binding assay with recombinant 2B4, anti-CD48 mAb blocking, surface plasmon resonance","journal":"The Journal of experimental medicine","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — direct binding assay plus quantitative SPR, replicated independently in same year (PMID:9834056)","pmids":["9841922"],"is_preprint":false},{"year":1998,"finding":"CD48 fusion protein (CD48-IgG1) identified 2B4 as a novel counter-receptor of CD48 by immunofluorescence and immunoprecipitation, independently confirming the CD48–2B4 interaction.","method":"Chimeric CD48-IgG1 fusion protein pulldown, immunofluorescence, immunoprecipitation","journal":"Journal of immunology (Baltimore, Md. : 1950)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — two orthogonal binding methods, independent confirmation of PMID:9841922","pmids":["9834056"],"is_preprint":false},{"year":1990,"finding":"Mouse BCM1/CD48 (also known as OX45/Blast-1) is a GPI-anchored glycoprotein expressed on leukocytes, cloned and sequenced. Genomic linkage analysis placed the Bcm-1 locus on distal mouse chromosome 1, linked to an ATPase alpha chain gene, establishing CD48 as a member of the CD2/LFA3 Ig superfamily subgroup.","method":"cDNA cloning and sequencing, genetic linkage mapping, pulse-field gel electrophoresis","journal":"The Journal of experimental medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — cDNA cloning with sequence analysis and genetic mapping; structural inference of GPI anchor","pmids":["1693656"],"is_preprint":false},{"year":1991,"finding":"CD48 (Blast-1) is expressed on T cells and monocytes in addition to B cells. EBV transformation and PMA/IL-4/PHA stimulation increase surface CD48 expression by elevating steady-state CD48 mRNA. A subset of CD48 molecules is resistant to GPI-specific phospholipase C digestion and may exist in a complexed form on the cell surface.","method":"Immunoprecipitation, immunofluorescence, Northern blot, GPI-PLC digestion, Cos-7 transfection","journal":"Journal of immunology (Baltimore, Md. : 1950)","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — multiple biochemical and cellular methods in one study","pmids":["1848579"],"is_preprint":false},{"year":1999,"finding":"Engagement of 2B4 on human NK cells by anti-2B4 mAb or by CD48 (its ligand) triggers NK cell-mediated cytotoxicity. 2B4 is also expressed on monocytes and basophils, but 2B4 ligation does not activate T cells or monocytes, indicating cell-type-specific signaling downstream of the 2B4–CD48 interaction.","method":"Cytotoxicity assays using anti-2B4 mAb and recombinant CD48 protein, flow cytometry, molecular cloning of human 2B4","journal":"European journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — functional cytotoxicity assay with recombinant CD48 ligand, single laboratory","pmids":["10359122"],"is_preprint":false},{"year":1999,"finding":"CD48-deficient mice (generated by gene targeting) display a profound defect in CD4⁺ T cell activation: proliferative responses to mitogens, anti-CD3 mAb, and alloantigen are all reduced. CD48 is required on both T cells and antigen-presenting cells. The most dramatic impairment occurs when highly purified T cells are stimulated through the TCR plus PMA, suggesting CD48 plays a role in TCR signaling.","method":"Gene targeting (knockout mice), co-culture proliferation assays, mitogen and alloantigen stimulation assays","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean genetic knockout with multiple functional readouts; CD48 requirement demonstrated on both T cells and APCs by cell mixing experiments","pmids":["9927686"],"is_preprint":false},{"year":1999,"finding":"NAIL (human 2B4 homologue, later NTB-A) binds CD48 as its counter-receptor. Recombinant CD48 protein enhances NK cell cytotoxicity and induces IFN-γ production. Soluble NAIL-Fc stimulates B cell proliferation and DC IL-12/TNF-α release, demonstrating that CD48–NAIL/2B4 interactions regulate multiple immune cell responses.","method":"Soluble fusion protein binding assays, NK cytotoxicity assays, IFN-γ ELISA, B cell proliferation, DC cytokine assays","journal":"European journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — multiple functional assays with recombinant CD48, single laboratory","pmids":["10556801"],"is_preprint":false},{"year":2000,"finding":"CD48 co-clusters with IL-2Rα and HLA molecules in cholesterol-dependent lipid raft microdomains (~600–800 nm clusters) on T lymphoma cells. Disruption of membrane cholesterol with filipin or methyl-β-cyclodextrin disperses these clusters, whereas the transferrin receptor (non-raft) clusters are largely unaffected and do not co-localize with CD48.","method":"Immunogold staining/electron microscopy, confocal microscopy, cholesterol depletion, crosscorrelation analysis","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — two imaging modalities with cholesterol-depletion perturbation; single study","pmids":["10823948"],"is_preprint":false},{"year":2002,"finding":"Direct force measurements using surface force apparatus confirmed that the full-length extracellular domains of CD2 and CD48 adhere in a head-to-head orientation, with no long-range electrostatic attraction, abrupt adhesive failure (no partial unfolding), and weak adhesion requiring lateral receptor mobility. This is the first direct measurement of forces governing CD2–CD48 heterotypic adhesion.","method":"Direct surface force measurements between protein-coated lipid bilayers","journal":"Biochemistry","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — unique biophysical reconstitution method, single study, single laboratory","pmids":["12356317"],"is_preprint":false},{"year":2003,"finding":"CD48 on mast cells aggregates at sites of Mycobacterium tuberculosis binding, and anti-CD48 antibodies inhibit histamine release triggered by mycobacteria, implicating CD48 as a receptor mediating mast cell recognition of and activation by M. tuberculosis.","method":"Confocal microscopy of CD48 aggregation at bacterial binding sites, anti-CD48 mAb inhibition of histamine release","journal":"Journal of immunology (Baltimore, Md. : 1950)","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — two orthogonal approaches (localization + functional inhibition), single study","pmids":["12759438"],"is_preprint":false},{"year":2005,"finding":"Homotypic 2B4/CD48 interactions among NK cells are essential for IL-2-driven NK cell expansion, cytotoxicity, and IFN-γ secretion; CD2/CD48 interactions on NK cells are not required for these functions. 2B4-deficient but not CD2-deficient NK cells fail to clear syngeneic tumor cells in vivo. Defective 2B4/CD48 signaling correlates with impaired calcium signaling. GFP-tagged 2B4 localizes specifically to NK–NK conjugation sites, confirming homotypic trans-interaction.","method":"Gene-deficient NK cells (2B4⁻/⁻, CD48⁻/⁻), cytotoxicity assays, IFN-γ ELISA, calcium imaging, GFP-2B4 live-cell imaging, in vivo tumor clearance","journal":"Blood","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods including KO mice, live imaging, signaling assays, and in vivo tumor model","pmids":["15905190"],"is_preprint":false},{"year":2005,"finding":"Site-directed mutagenesis of human 2B4 identified Lys68 and Glu70 in the V domain as critical residues for CD48 binding and for 2B4-mediated functional activation of human NK cells; double Lys68Ala/Glu70Ala mutant abolishes CD48-Fc binding and NK activation.","method":"Site-directed mutagenesis, flow cytometry binding assay with CD48-Fc fusion protein, NK cell functional activation assay","journal":"Journal of immunology (Baltimore, Md. : 1950)","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — mutagenesis with defined functional readout, single laboratory","pmids":["16002700"],"is_preprint":false},{"year":2006,"finding":"Crystal structure of the receptor-binding domain of rat CD48 resolved. The receptor-binding surface is unusually flat and electrostatically complementary to CD2. Thermodynamic analysis showed CD48–CD2 binding is driven by equivalent weak enthalpic and entropic contributions, distinct from the human CD2–CD58 interaction (which has a large entropic barrier). The flat, charge-complementary topology explains why CD48 can cross-react with both CD2 and 2B4/CD244.","method":"X-ray crystallography, isothermal titration calorimetry/thermodynamic binding analysis, comparative structural modelling","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure combined with quantitative thermodynamic analysis in a single study","pmids":["16803907"],"is_preprint":false},{"year":2006,"finding":"CD48 is an IL-3-inducible activating receptor on human eosinophils; cross-linking CD48 triggers release of eosinophil granule proteins (degranulation). In a murine asthma model, CD48 expression is induced by allergen challenge and partially regulated by IL-3; anti-IL-3 reduces both CD48 expression and airway inflammation.","method":"Flow cytometry, antibody cross-linking degranulation assays, murine OVA asthma model, anti-IL-3 antibody treatment","journal":"Journal of immunology (Baltimore, Md. : 1950)","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — in vitro cross-linking assay plus in vivo mouse model, single laboratory","pmids":["16785501"],"is_preprint":false},{"year":2006,"finding":"CD48 controls both T cell and APC function in experimental colitis. CD48⁻/⁻ CD4⁺ T cells fail to induce colitis when transferred into CD48⁻/⁻ × Rag-2⁻/⁻ recipients (but can into Rag-2⁻/⁻ hosts), indicating CD48 is required on APCs in the recipient to drive disease. CD48⁻/⁻ macrophages produce less TNF-α and IL-12 upon LPS stimulation and show defective bacterial clearance. Anti-CD48 mAb treatment ameliorates colitis even after disease onset.","method":"Adoptive transfer colitis model using CD48⁻/⁻ and Rag-2⁻/⁻ mice, in vitro macrophage stimulation assays, anti-CD48 therapeutic treatment","journal":"Gastroenterology","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean KO genetics, cell-transfer epistasis, multiple in vitro functional assays, therapeutic intervention","pmids":["16472597"],"is_preprint":false},{"year":2009,"finding":"GPI-anchored CD48 (but not CD59) is recruited to the immobilized TCR/CD3 complex upon T cell activation. CD48 reorganization is required for LAT association with the TCR/CD3 complex and for IL-2 production. CD2 acts upstream of CD48: CD2 associates with TCR/CD3 independently of CD48 and recruits Lck, while CD48 recruitment and subsequent LAT association depend on CD2. Thus CD2 and CD48 cooperate hierarchically to build the early TCR signalosome.","method":"Co-immunoprecipitation, proximity ligation/signalosome reconstitution assays, CD48 knockdown/knockout T cells, IL-2 ELISA, LAT co-precipitation","journal":"Journal of immunology (Baltimore, Md. : 1950)","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP establishing hierarchical pathway placement, CD48-specific siRNA knockdown plus KO confirmation, multiple signaling readouts","pmids":["19494291"],"is_preprint":false},{"year":1997,"finding":"Both type I (α/β) and type II (γ) interferons upregulate CD48 mRNA and surface protein expression on multiple human cell lines and peripheral blood CD3⁺, CD14⁺, and CD19⁺ subsets; IFN has no corresponding effect on LFA-3 expression.","method":"Northern blot, flow cytometry, IFN treatment of human cell lines and PBMCs","journal":"Journal of interferon & cytokine research","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — two orthogonal methods (mRNA and protein), multiple cell types examined, single laboratory","pmids":["9041467"],"is_preprint":false},{"year":2013,"finding":"ORMDL3, an ER-localized protein, regulates IL-3-induced CD48 expression on eosinophils and mediates CD48-dependent eosinophil degranulation; ORMDL3 knockdown significantly inhibits eosinophil degranulation and in vivo recruitment.","method":"ORMDL3 overexpression and siRNA knockdown in eosinophils, flow cytometry, in vivo murine asthma model, degranulation assays","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — gain- and loss-of-function with in vivo confirmation, single laboratory","pmids":["24056518"],"is_preprint":false},{"year":2014,"finding":"CD48 on human and murine eosinophils serves as a receptor mediating Staphylococcus aureus and its exotoxins (SEB, protein A, peptidoglycan) activation: SA/exotoxins physically bind to CD48, cause eosinophil degranulation, cytokine release, and signal transduction; these effects are significantly reduced by CD48 blocking or in CD48⁻/⁻ bone marrow eosinophils. In vivo, CD48⁻/⁻ mice show reduced eosinophil recruitment in SEB-induced peritonitis.","method":"Confocal microscopy of SA binding to CD48, adhesion and degranulation assays, cytokine ELISA, CD48⁻/⁻ mouse peritonitis model","journal":"Clinical and experimental allergy","confidence":"High","confidence_rationale":"Tier 2 / Strong — physical interaction shown by microscopy, multiple functional readouts, KO confirmation both in vitro and in vivo","pmids":["25255823"],"is_preprint":false},{"year":2014,"finding":"Engagement of SLAMF2/CD48 on dendritic cells (DCs) by SLAMF4 recombinant protein or anti-SLAMF2 Ab activates immature DCs and prolongs survival of DNA-activated DCs by inhibiting IFN-β production and IFN-β-induced apoptosis, and by promoting production of the granzyme B inhibitor protease inhibitor-9.","method":"Anti-SLAMF2 mAb and recombinant SLAMF4 protein engagement of DCs, IFN-β ELISA, apoptosis assays, granzyme B inhibitor measurement","journal":"Journal of immunology (Baltimore, Md. : 1950)","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — multiple functional endpoints but signaling mechanism inferred indirectly, single laboratory","pmids":["24670806"],"is_preprint":false},{"year":2016,"finding":"2B4 on NK cells interacts with CD48 both in trans (on neighbouring cells) and in cis (on the same NK cell surface), using the same binding site. Cis interaction induces basal 2B4 phosphorylation but reduces trans-binding to CD48-positive target cells; interfering with cis interaction enhanced lysis of CD48-expressing tumour cells.","method":"Proximity ligation assay, FRET, anti-2B4 blocking to perturb cis interaction, cytotoxicity assays","journal":"Open biology","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — multiple biochemical and functional assays demonstrating cis interaction, single laboratory","pmids":["27249817"],"is_preprint":false},{"year":2019,"finding":"A cytomegalovirus-encoded soluble CD48 homologue (A43, encoded by owl monkey CMV) is secreted after proteolytic processing and binds human 2B4 with high affinity and slow dissociation rate (SPR). A43 abrogates host CD48:2B4 interactions, reduces NK–target conjugate formation and immunological synapse establishment, and impairs 2B4-mediated cytotoxicity and IFN-γ production by NK cells.","method":"Surface plasmon resonance, NK cell cytotoxicity assays, conjugate formation assays, immunological synapse imaging, IFN-γ ELISA","journal":"PLoS pathogens","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — quantitative SPR plus multiple orthogonal functional assays, mechanistically establishes CD48–2B4 axis as viral immune evasion target","pmids":["30947296"],"is_preprint":false},{"year":2020,"finding":"CD48 expression in AML cells is epigenetically regulated by DNA methylation; treatment with a hypomethylating agent increases CD48 expression on AML cells and enhances NK cell killing of AML cells in vitro. Restoration of CD48 expression reverses AML immune evasion and activates NK cell function in vivo.","method":"Methylation analysis, hypomethylating agent treatment, NK cytotoxicity assays in vitro and in vivo mouse model","journal":"Clinical science (London, England : 1979)","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — epigenetic mechanism demonstrated with functional NK killing readout, in vivo confirmation, single laboratory","pmids":["31922199"],"is_preprint":false},{"year":2020,"finding":"Human innate lymphoid cell precursors (ILCPs) express CD48, and the interaction of 2B4 (on NKPs) with CD48 (on ILCPs) promotes differentiation of ILC2s; 2B4–CD48 signaling modulates ILC lineage commitment.","method":"Flow cytometry of precursor subsets, in vitro differentiation assays, in vivo humanized mouse model","journal":"Science immunology","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — defined precursor subsets with functional differentiation assay and in vivo confirmation, single laboratory","pmids":["33219153"],"is_preprint":false},{"year":2021,"finding":"GDF15 binds CD48 as a previously unrecognized receptor on T cells, thereby downregulating STUB1 (an E3 ubiquitin ligase that mediates FOXP3 degradation), which promotes generation of peripheral iTreg cells and enhances suppressive function of nTreg cells; GDF15 neutralizing antibody eradicates HCC in mouse models.","method":"Co-immunoprecipitation, mass spectrometry, RNA sequencing, ChIP, flow cytometry (CyTOF), GDF15-knockout HCC mouse model, hybridoma-generated neutralizing mAb","journal":"Journal for immunotherapy of cancer","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP and mass spec identification of CD48 as GDF15 receptor with multiple downstream mechanistic assays, single laboratory; novel finding not yet independently replicated","pmids":["34489334"],"is_preprint":false},{"year":2022,"finding":"Genome-wide CRISPR screens in ATLL cell lines identified CD48 as the top gene whose knockout confers resistance to NK-cell-mediated cytotoxicity; CD48-knockout ATLL cells evade NK-cell effector function (reduced IFN-γ induction and degranulation by primary human NK cells). Primary ATLL cells show reduced CD48 expression with disease progression.","method":"Genome-wide CRISPR knockout screen, flow cytometry, NK cytotoxicity assays with primary human NK cells","journal":"Blood","confidence":"High","confidence_rationale":"Tier 2 / Strong — unbiased genome-wide screen confirmed with primary human NK cells and primary patient samples, two cell lines tested","pmids":["35921533"],"is_preprint":false},{"year":2024,"finding":"KDM6A loss leads to increased H3K27me3 on the CD48 promoter, causing CD48 downregulation in multiple myeloma cells. EZH2 inhibitor treatment restores CD48 (and CD38) expression and reverses resistance to Daratumumab-mediated ADCC, establishing KDM6A/EZH2/H3K27me3 as an epigenetic axis regulating CD48 expression.","method":"Genome-wide CRISPR screens, ChIP for H3K27me3 on CD48 promoter, EZH2 inhibitor treatment, CD38/CD48 re-expression, ADCC assays","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — CRISPR screen plus ChIP mechanistic validation plus pharmacological rescue, two orthogonal KDM6A-loss models","pmids":["38355622"],"is_preprint":false}],"current_model":"CD48 is a GPI-anchored Ig-superfamily glycoprotein expressed broadly on hematopoietic cells that functions as an adhesion and co-stimulatory ligand: it binds CD2 with very low affinity (KD ~60–90 µM, head-to-head via GFCC'C'' beta-sheet surfaces as resolved by mutagenesis, NMR, and X-ray crystallography) and binds its high-affinity ligand 2B4/CD244 (KD ~8–16 µM), thereby co-stimulating T cell activation (by recruiting LAT to the TCR/CD3 signalosome downstream of CD2/Lck), regulating NK cell cytotoxicity and IFN-γ production (including through homotypic NK–NK 2B4/CD48 interactions), activating eosinophils and mast cells (including in response to bacterial pathogens such as M. tuberculosis and S. aureus), and modulating DC survival; CD48 expression is upregulated by interferons and IL-3 and is epigenetically repressed by EZH2/H3K27me3 (controlled by KDM6A), and CD48 has additionally been identified as a receptor for GDF15 on Treg cells linking tumor-derived signals to immunosuppression."},"narrative":{"mechanistic_narrative":"CD48 is a GPI-anchored Ig-superfamily glycoprotein expressed broadly on hematopoietic cells that functions as a heterotypic adhesion and co-stimulatory ligand coordinating T cell, NK cell, and innate immune responses [PMID:1383383, PMID:1693656]. It engages CD2 as a counter-receptor through a very low-affinity, fast-dissociating interaction (KD ~60–90 µM) mediated by the GFCC'C'' beta-sheet face of its membrane-distal Ig domain in a head-to-head docking topology, a binding mode confirmed biophysically and crystallographically as an unusually flat, charge-complementary surface [PMID:1383383, PMID:7903240, PMID:7697352, PMID:16803907]. The same flat surface allows CD48 to cross-react with its higher-affinity ligand 2B4/CD244 (KD ~8–16 µM), and these CD48–2B4 interactions—including homotypic NK–NK engagement—drive NK cell cytotoxicity and IFN-γ production [PMID:9841922, PMID:15905190, PMID:16803907]. In T cells, GPI-anchored CD48 is recruited to the immobilized TCR/CD3 complex downstream of CD2/Lck and is required for LAT association and IL-2 production, placing CD48 in a hierarchical co-stimulatory pathway that builds the early TCR signalosome [PMID:9927686, PMID:19494291]. Beyond lymphocytes, CD48 acts as an activating receptor on eosinophils and mast cells, mediating recognition of bacterial pathogens including M. tuberculosis and S. aureus and triggering degranulation [PMID:12759438, PMID:16785501, PMID:25255823]. CD48 surface expression is induced by type I/II interferons and IL-3 and is epigenetically repressed via H3K27me3 deposition on its promoter, an axis controlled by KDM6A/EZH2 and by DNA methylation that tumors exploit to evade NK-mediated killing [PMID:16785501, PMID:9041467, PMID:35921533, PMID:38355622]. CD48 has additionally been identified as a receptor for GDF15 on T cells, linking tumor-derived signals to Treg-mediated immunosuppression [PMID:34489334].","teleology":[{"year":1990,"claim":"Establishing CD48 as a cloned GPI-anchored leukocyte glycoprotein of the CD2/LFA3 Ig superfamily subgroup defined the molecular identity from which all functional studies proceeded.","evidence":"cDNA cloning, sequencing, and genetic linkage mapping of mouse BCM1/CD48","pmids":["1693656"],"confidence":"Medium","gaps":["GPI anchor inferred structurally rather than directly demonstrated","no ligand or function assigned at this stage"]},{"year":1992,"claim":"Identifying CD48 as the counter-receptor for CD2 answered what physiological ligand engages this molecule and connected it to T cell adhesion.","evidence":"Chimeric CD2-IgG pulldown, protein microsequencing, and mAb blocking in T cell lines","pmids":["1383383"],"confidence":"High","gaps":["affinity and kinetics of the interaction not quantified","binding interface not mapped"]},{"year":1993,"claim":"Quantitative SPR established that CD2–CD48 is an extremely low-affinity, fast-off-rate interaction, defining the biophysical regime of cell-surface adhesion-receptor recognition.","evidence":"Surface plasmon resonance with soluble recombinant proteins in both orientations; confirmed by analytical ultracentrifugation","pmids":["7903240","9188168"],"confidence":"High","gaps":["does not explain how weak affinity is translated into productive signaling","structural basis of binding not resolved"]},{"year":1996,"claim":"Mapping the binding surface to the GFCC'C'' beta-sheet face on both CD48 and CD2 established the head-to-head docking topology and the structural origin of species specificity.","evidence":"Complementary charge-swap mutagenesis, heteronuclear NMR titration, and molecular modelling","pmids":["7697352","8634239"],"confidence":"High","gaps":["high-resolution crystal structure not yet available","thermodynamic basis of recognition not determined"]},{"year":1998,"claim":"Identifying 2B4/CD244 as a second, higher-affinity ligand revealed that CD48 functions in more than one receptor axis and engages activating receptors beyond CD2.","evidence":"Recombinant 2B4 binding assays, anti-CD48 blocking, and SPR; independent CD48-IgG1 pulldown confirmation","pmids":["9841922","9834056"],"confidence":"High","gaps":["downstream signaling of the 2B4–CD48 interaction not yet defined","relative physiological role of CD2 vs 2B4 engagement unclear"]},{"year":1999,"claim":"Genetic knockout demonstrated that CD48 is functionally required on both T cells and APCs for CD4+ T cell activation, and that CD48–2B4 engagement controls NK cytotoxicity and IFN-γ, moving CD48 from a binding partner to a causal regulator of immune function.","evidence":"CD48-deficient mice with proliferation/cell-mixing assays; NK cytotoxicity and IFN-γ assays with recombinant CD48 and NAIL/2B4 homologue","pmids":["9927686","10359122","10556801"],"confidence":"High","gaps":["molecular mechanism linking GPI-anchored CD48 to TCR signaling not resolved","signaling events downstream of CD48 in APCs unmapped"]},{"year":2000,"claim":"Demonstrating that CD48 co-clusters with IL-2Rα and HLA in cholesterol-dependent lipid rafts provided a membrane-organization basis for how a GPI-anchored molecule participates in signaling.","evidence":"Immunogold/EM and confocal imaging with cholesterol depletion on T lymphoma cells","pmids":["10823948"],"confidence":"Medium","gaps":["functional consequence of raft clustering for signaling not directly tested","single cell type examined"]},{"year":2006,"claim":"The crystal structure plus thermodynamic analysis explained how an unusually flat, charge-complementary CD48 surface enables cross-reactivity with both CD2 and 2B4, resolving the structural logic of dual ligand recognition.","evidence":"X-ray crystallography of rat CD48 receptor-binding domain with isothermal titration calorimetry; surface force measurements of CD2–CD48 adhesion","pmids":["16803907","12356317"],"confidence":"High","gaps":["structure of the full CD48–2B4 complex not solved","structures from rat domains rather than human"]},{"year":2009,"claim":"Placing CD48 hierarchically downstream of CD2/Lck and upstream of LAT recruitment defined the mechanistic logic by which CD2 and CD48 cooperate to assemble the early TCR signalosome.","evidence":"Reciprocal Co-IP, CD48 knockdown/knockout T cells, LAT co-precipitation, and IL-2 readouts","pmids":["19494291"],"confidence":"High","gaps":["how a GPI-anchored protein lacking a cytoplasmic tail transmits the signal not fully explained","physical link between CD48 and LAT not identified"]},{"year":2014,"claim":"Establishing CD48 as a receptor for whole bacteria and exotoxins on eosinophils and mast cells, and as a survival-modulating receptor on DCs, broadened CD48 function from lymphocyte co-stimulation to innate pathogen sensing and myeloid regulation.","evidence":"M. tuberculosis and S. aureus binding/degranulation assays with anti-CD48 blocking and CD48−/− eosinophils; SLAMF4/anti-SLAMF2 engagement of DCs","pmids":["12759438","16785501","25255823","24670806"],"confidence":"High","gaps":["molecular details of bacterial ligand binding to CD48 not defined","signaling pathway from CD48 to degranulation unresolved"]},{"year":2020,"claim":"Defining IFN-, IL-3-, DNA-methylation- and KDM6A/EZH2-dependent control of CD48 surface expression established how CD48 levels are tuned and how tumors silence CD48 to escape NK-mediated and antibody-dependent killing.","evidence":"IFN/IL-3 induction assays; ORMDL3 manipulation; methylation and H3K27me3 ChIP with hypomethylating and EZH2-inhibitor rescue and NK/ADCC readouts in AML and myeloma","pmids":["9041467","16785501","24056518","31922199","38355622"],"confidence":"High","gaps":["transcription factors directly driving CD48 from these signals not fully defined","relative contribution of DNA methylation vs H3K27me3 across tumor types unclear"]},{"year":2021,"claim":"Identifying CD48 as a receptor for GDF15 on T cells linked tumor-derived signals to Treg-mediated immunosuppression via STUB1/FOXP3, expanding CD48's ligand repertoire beyond Ig-superfamily counter-receptors.","evidence":"Co-IP/mass spectrometry receptor identification with downstream RNA-seq, ChIP, CyTOF and a GDF15-KO HCC model","pmids":["34489334"],"confidence":"Medium","gaps":["GDF15–CD48 binding not independently replicated","structural basis of GDF15 engagement of CD48 unknown"]},{"year":2022,"claim":"Unbiased CRISPR screens nominated CD48 as the dominant determinant of tumor susceptibility to NK-cell killing, cementing the CD48–2B4 axis as a clinically relevant immune-evasion target.","evidence":"Genome-wide CRISPR knockout screens in ATLL lines with primary human NK cytotoxicity assays and patient samples","pmids":["35921533"],"confidence":"High","gaps":["mechanism of CD48 loss in primary disease progression not defined","interplay between CD48 and other NK ligands not addressed"]},{"year":null,"claim":"How a cytoplasmic-tail-less GPI-anchored CD48 physically transduces signals into the TCR signalosome and into innate effector pathways, and whether the GDF15–CD48 axis generalizes, remain open.","evidence":"","pmids":[],"confidence":"Medium","gaps":["no defined cytoplasmic transducer for GPI-anchored CD48","GDF15–CD48 interaction awaits independent confirmation","no human-protein high-resolution structure of CD48–2B4 or CD48–GDF15 complexes"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0048018","term_label":"receptor ligand activity","supporting_discovery_ids":[0,5,11,29]},{"term_id":"GO:0060089","term_label":"molecular transducer activity","supporting_discovery_ids":[14,18,23]},{"term_id":"GO:0098631","term_label":"cell adhesion mediator activity","supporting_discovery_ids":[0,2,13]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[7,8,12]}],"pathway":[{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[10,15,20,30]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[20,29]}],"complexes":[],"partners":["CD2","CD244","GDF15"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P09326","full_name":"CD48 antigen","aliases":["B-lymphocyte activation marker BLAST-1","BCM1 surface antigen","Leukocyte antigen MEM-102","SLAM family member 2","SLAMF2","Signaling lymphocytic activation molecule 2","TCT.1"],"length_aa":243,"mass_kda":27.7,"function":"Glycosylphosphatidylinositol (GPI)-anchored cell surface glycoprotein that interacts via its N-terminal immunoglobulin domain with cell surface receptors including CD244/2B4 or CD2 to regulate immune cell function and activation (PubMed:12007789, PubMed:19494291, PubMed:27249817, PubMed:9841922). Participates in T-cell signaling transduction by associating with CD2 and efficiently bringing the Src family protein kinase LCK and LAT to the TCR/CD3 complex (PubMed:19494291). In turn, promotes LCK phosphorylation and subsequent activation (PubMed:12007789). Induces the phosphorylation of the cytoplasmic immunoreceptortyrosine switch motifs (ITSMs) of CD244 initiating a series of signaling events that leads to the generation of the immunological synapse and the directed release of cytolytic granules containing perforin and granzymes by T-lymphocytes and NK-cells (PubMed:27249817)","subcellular_location":"Cell membrane; Membrane raft; Secreted","url":"https://www.uniprot.org/uniprotkb/P09326/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/CD48","classification":"Not Classified","n_dependent_lines":3,"n_total_lines":1208,"dependency_fraction":0.0024834437086092716},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/CD48","total_profiled":1310},"omim":[{"mim_id":"606625","title":"SLAM FAMILY, MEMBER 7; SLAMF7","url":"https://www.omim.org/entry/606625"},{"mim_id":"606620","title":"SLAM FAMILY, MEMBER 8; SLAMF8","url":"https://www.omim.org/entry/606620"},{"mim_id":"606446","title":"SLAM FAMILY, MEMBER 6; SLAMF6","url":"https://www.omim.org/entry/606446"},{"mim_id":"605554","title":"CD244 ANTIGEN; CD244","url":"https://www.omim.org/entry/605554"},{"mim_id":"604513","title":"CD84 ANTIGEN; CD84","url":"https://www.omim.org/entry/604513"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Plasma membrane","reliability":"Approved"},{"location":"Nucleoli fibrillar center","reliability":"Additional"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Group enriched","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"bone marrow","ntpm":140.1},{"tissue":"lymphoid tissue","ntpm":265.6}],"url":"https://www.proteinatlas.org/search/CD48"},"hgnc":{"alias_symbol":["BLAST","mCD48","hCD48","SLAMF2"],"prev_symbol":["BCM1"]},"alphafold":{"accession":"P09326","domains":[{"cath_id":"2.60.40.10","chopping":"31-129","consensus_level":"high","plddt":95.1989,"start":31,"end":129},{"cath_id":"2.60.40.10","chopping":"136-218","consensus_level":"high","plddt":90.0041,"start":136,"end":218}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P09326","model_url":"https://alphafold.ebi.ac.uk/files/AF-P09326-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P09326-F1-predicted_aligned_error_v6.png","plddt_mean":82.81},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=CD48","jax_strain_url":"https://www.jax.org/strain/search?query=CD48"},"sequence":{"accession":"P09326","fasta_url":"https://rest.uniprot.org/uniprotkb/P09326.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P09326/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P09326"}},"corpus_meta":[{"pmid":"9254694","id":"PMC_9254694","title":"Gapped BLAST and PSI-BLAST: a new generation of protein database search programs.","date":"1997","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/9254694","citation_count":53770,"is_preprint":false},{"pmid":"20003500","id":"PMC_20003500","title":"BLAST+: architecture and applications.","date":"2009","source":"BMC bioinformatics","url":"https://pubmed.ncbi.nlm.nih.gov/20003500","citation_count":15253,"is_preprint":false},{"pmid":"11932250","id":"PMC_11932250","title":"BLAT--the BLAST-like alignment tool.","date":"2002","source":"Genome research","url":"https://pubmed.ncbi.nlm.nih.gov/11932250","citation_count":6510,"is_preprint":false},{"pmid":"22593173","id":"PMC_22593173","title":"Chronic traumatic encephalopathy in blast-exposed military veterans and a blast neurotrauma mouse model.","date":"2012","source":"Science translational medicine","url":"https://pubmed.ncbi.nlm.nih.gov/22593173","citation_count":765,"is_preprint":false},{"pmid":"22510480","id":"PMC_22510480","title":"Domain enhanced lookup time accelerated BLAST.","date":"2012","source":"Biology direct","url":"https://pubmed.ncbi.nlm.nih.gov/22510480","citation_count":628,"is_preprint":false},{"pmid":"14982876","id":"PMC_14982876","title":"The biology of CML blast crisis.","date":"2004","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/14982876","citation_count":423,"is_preprint":false},{"pmid":"6172535","id":"PMC_6172535","title":"A nuclear antigen associated with cell proliferation and blast transformation.","date":"1981","source":"The Journal of experimental medicine","url":"https://pubmed.ncbi.nlm.nih.gov/6172535","citation_count":350,"is_preprint":false},{"pmid":"9841922","id":"PMC_9841922","title":"2B4, the natural killer and T cell immunoglobulin superfamily surface protein, is a ligand for CD48.","date":"1998","source":"The Journal of experimental medicine","url":"https://pubmed.ncbi.nlm.nih.gov/9841922","citation_count":328,"is_preprint":false},{"pmid":"16709195","id":"PMC_16709195","title":"A B-lectin receptor kinase gene conferring rice blast resistance.","date":"2006","source":"The Plant journal : for cell and molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/16709195","citation_count":294,"is_preprint":false},{"pmid":"1383383","id":"PMC_1383383","title":"CD48 is a counter-receptor for mouse CD2 and is involved in T cell activation.","date":"1992","source":"The Journal of experimental medicine","url":"https://pubmed.ncbi.nlm.nih.gov/1383383","citation_count":247,"is_preprint":false},{"pmid":"10359122","id":"PMC_10359122","title":"Activating interactions in human NK cell recognition: the role of 2B4-CD48.","date":"1999","source":"European journal of immunology","url":"https://pubmed.ncbi.nlm.nih.gov/10359122","citation_count":208,"is_preprint":false},{"pmid":"26794910","id":"PMC_26794910","title":"Roles of CD48 in regulating immunity and tolerance.","date":"2016","source":"Clinical immunology (Orlando, Fla.)","url":"https://pubmed.ncbi.nlm.nih.gov/26794910","citation_count":171,"is_preprint":false},{"pmid":"34489334","id":"PMC_34489334","title":"GDF15 induces immunosuppression via CD48 on regulatory T cells in hepatocellular carcinoma.","date":"2021","source":"Journal for immunotherapy of cancer","url":"https://pubmed.ncbi.nlm.nih.gov/34489334","citation_count":137,"is_preprint":false},{"pmid":"20627803","id":"PMC_20627803","title":"Recent advances in rice blast effector research.","date":"2010","source":"Current opinion in plant biology","url":"https://pubmed.ncbi.nlm.nih.gov/20627803","citation_count":132,"is_preprint":false},{"pmid":"9834056","id":"PMC_9834056","title":"Identification of the 2B4 molecule as a counter-receptor for CD48.","date":"1998","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/9834056","citation_count":130,"is_preprint":false},{"pmid":"10823948","id":"PMC_10823948","title":"Cholesterol-dependent clustering of IL-2Ralpha and its colocalization with HLA and CD48 on T lymphoma cells suggest their functional association with lipid rafts.","date":"2000","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/10823948","citation_count":126,"is_preprint":false},{"pmid":"32367535","id":"PMC_32367535","title":"Ferroptosis contributes to developmental cell death in rice blast.","date":"2020","source":"The New phytologist","url":"https://pubmed.ncbi.nlm.nih.gov/32367535","citation_count":125,"is_preprint":false},{"pmid":"34111285","id":"PMC_34111285","title":"Distinguishing AML from MDS: a fixed blast percentage may no longer be optimal.","date":"2022","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/34111285","citation_count":123,"is_preprint":false},{"pmid":"7697352","id":"PMC_7697352","title":"Topology of the CD2-CD48 cell-adhesion molecule complex: implications for antigen recognition by T cells.","date":"1995","source":"Current biology : CB","url":"https://pubmed.ncbi.nlm.nih.gov/7697352","citation_count":119,"is_preprint":false},{"pmid":"18480120","id":"PMC_18480120","title":"GeneCAT--novel webtools that combine BLAST and co-expression analyses.","date":"2008","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/18480120","citation_count":116,"is_preprint":false},{"pmid":"7903240","id":"PMC_7903240","title":"Affinity and kinetic analysis of the interaction of the cell adhesion molecules rat CD2 and CD48.","date":"1993","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/7903240","citation_count":114,"is_preprint":false},{"pmid":"30975460","id":"PMC_30975460","title":"RRM Transcription Factors Interact with NLRs and Regulate Broad-Spectrum Blast Resistance in Rice.","date":"2019","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/30975460","citation_count":106,"is_preprint":false},{"pmid":"17905473","id":"PMC_17905473","title":"Susceptibility of rice to the blast fungus, Magnaporthe grisea.","date":"2007","source":"Journal of plant physiology","url":"https://pubmed.ncbi.nlm.nih.gov/17905473","citation_count":105,"is_preprint":false},{"pmid":"1693656","id":"PMC_1693656","title":"Structure, expression, and genetic linkage of the mouse BCM1 (OX45 or Blast-1) antigen. Evidence for genetic duplication giving rise to the BCM1 region on mouse chromosome 1 and the CD2/LFA3 region on mouse chromosome 3.","date":"1990","source":"The Journal of experimental medicine","url":"https://pubmed.ncbi.nlm.nih.gov/1693656","citation_count":103,"is_preprint":false},{"pmid":"27641772","id":"PMC_27641772","title":"Immunity to Rice Blast Disease by Suppression of Effector-Triggered Necrosis.","date":"2016","source":"Current biology : CB","url":"https://pubmed.ncbi.nlm.nih.gov/27641772","citation_count":99,"is_preprint":false},{"pmid":"24056518","id":"PMC_24056518","title":"ORMDL3 promotes eosinophil trafficking and activation via regulation of integrins and CD48.","date":"2013","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/24056518","citation_count":98,"is_preprint":false},{"pmid":"7903681","id":"PMC_7903681","title":"Anti-CD2 receptor and anti-CD2 ligand (CD48) antibodies synergize to prolong allograft survival.","date":"1994","source":"The Journal of experimental medicine","url":"https://pubmed.ncbi.nlm.nih.gov/7903681","citation_count":95,"is_preprint":false},{"pmid":"1848579","id":"PMC_1848579","title":"Expression of the Blast-1 activation/adhesion molecule and its identification as CD48.","date":"1991","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/1848579","citation_count":91,"is_preprint":false},{"pmid":"21861635","id":"PMC_21861635","title":"Factors affecting blast traumatic brain injury.","date":"2011","source":"Journal of neurotrauma","url":"https://pubmed.ncbi.nlm.nih.gov/21861635","citation_count":87,"is_preprint":false},{"pmid":"11163982","id":"PMC_11163982","title":"Using BLAST for identifying gene and protein names in journal articles.","date":"2000","source":"Gene","url":"https://pubmed.ncbi.nlm.nih.gov/11163982","citation_count":86,"is_preprint":false},{"pmid":"31513573","id":"PMC_31513573","title":"Effector gene reshuffling involves dispensable mini-chromosomes in the wheat blast fungus.","date":"2019","source":"PLoS genetics","url":"https://pubmed.ncbi.nlm.nih.gov/31513573","citation_count":86,"is_preprint":false},{"pmid":"24412978","id":"PMC_24412978","title":"EC-BLAST: a tool to automatically search and compare enzyme reactions.","date":"2014","source":"Nature methods","url":"https://pubmed.ncbi.nlm.nih.gov/24412978","citation_count":85,"is_preprint":false},{"pmid":"36943033","id":"PMC_36943033","title":"UniProt Tools: BLAST, Align, Peptide Search, and ID Mapping.","date":"2023","source":"Current protocols","url":"https://pubmed.ncbi.nlm.nih.gov/36943033","citation_count":84,"is_preprint":false},{"pmid":"10556801","id":"PMC_10556801","title":"Molecular cloning and biological characterization of NK cell activation-inducing ligand, a counterstructure for CD48.","date":"1999","source":"European journal of immunology","url":"https://pubmed.ncbi.nlm.nih.gov/10556801","citation_count":81,"is_preprint":false},{"pmid":"12759438","id":"PMC_12759438","title":"Mast cell activation by Mycobacterium tuberculosis: mediator release and role of CD48.","date":"2003","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/12759438","citation_count":80,"is_preprint":false},{"pmid":"15905190","id":"PMC_15905190","title":"Requirement of homotypic NK-cell interactions through 2B4(CD244)/CD48 in the generation of NK effector functions.","date":"2005","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/15905190","citation_count":75,"is_preprint":false},{"pmid":"9927686","id":"PMC_9927686","title":"CD48-deficient mice have a pronounced defect in CD4(+) T cell activation.","date":"1999","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/9927686","citation_count":74,"is_preprint":false},{"pmid":"27574197","id":"PMC_27574197","title":"Sequence Alignment and Homology Search with BLAST and ClustalW.","date":"2016","source":"Cold Spring Harbor protocols","url":"https://pubmed.ncbi.nlm.nih.gov/27574197","citation_count":71,"is_preprint":false},{"pmid":"18024655","id":"PMC_18024655","title":"The Biology of CML blast crisis.","date":"2007","source":"Hematology. American Society of Hematology. Education Program","url":"https://pubmed.ncbi.nlm.nih.gov/18024655","citation_count":70,"is_preprint":false},{"pmid":"19422293","id":"PMC_19422293","title":"Biomarkers of blast-induced neurotrauma: profiling molecular and cellular mechanisms of blast brain injury.","date":"2009","source":"Journal of neurotrauma","url":"https://pubmed.ncbi.nlm.nih.gov/19422293","citation_count":66,"is_preprint":false},{"pmid":"20833258","id":"PMC_20833258","title":"CD48: A co-stimulatory receptor of immunity.","date":"2010","source":"The international journal of biochemistry & cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/20833258","citation_count":62,"is_preprint":false},{"pmid":"27839570","id":"PMC_27839570","title":"Management of CML-blast crisis.","date":"2016","source":"Best practice & research. Clinical haematology","url":"https://pubmed.ncbi.nlm.nih.gov/27839570","citation_count":58,"is_preprint":false},{"pmid":"16785501","id":"PMC_16785501","title":"CD48 is an allergen and IL-3-induced activation molecule on eosinophils.","date":"2006","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/16785501","citation_count":51,"is_preprint":false},{"pmid":"25814082","id":"PMC_25814082","title":"Management of chronic myeloid leukemia in blast crisis.","date":"2015","source":"Annals of hematology","url":"https://pubmed.ncbi.nlm.nih.gov/25814082","citation_count":51,"is_preprint":false},{"pmid":"17993673","id":"PMC_17993673","title":"PSI-BLAST tutorial.","date":"2007","source":"Methods in molecular biology (Clifton, N.J.)","url":"https://pubmed.ncbi.nlm.nih.gov/17993673","citation_count":50,"is_preprint":false},{"pmid":"9418191","id":"PMC_9418191","title":"Detection of a soluble form of the leukocyte surface antigen CD48 in plasma and its elevation in patients with lymphoid leukemias and arthritis.","date":"1997","source":"Journal of clinical immunology","url":"https://pubmed.ncbi.nlm.nih.gov/9418191","citation_count":47,"is_preprint":false},{"pmid":"8634239","id":"PMC_8634239","title":"NMR analysis of interacting soluble forms of the cell-cell recognition molecules CD2 and CD48.","date":"1996","source":"Biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/8634239","citation_count":46,"is_preprint":false},{"pmid":"36952381","id":"PMC_36952381","title":"The OsBDR1-MPK3 module negatively regulates blast resistance by suppressing the jasmonate signaling and terpenoid biosynthesis pathway.","date":"2023","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/36952381","citation_count":43,"is_preprint":false},{"pmid":"29735658","id":"PMC_29735658","title":"Osmotic stabilization prevents cochlear synaptopathy after blast trauma.","date":"2018","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/29735658","citation_count":42,"is_preprint":false},{"pmid":"19494291","id":"PMC_19494291","title":"Sequential cooperation of CD2 and CD48 in the buildup of the early TCR signalosome.","date":"2009","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/19494291","citation_count":40,"is_preprint":false},{"pmid":"17290046","id":"PMC_17290046","title":"CD48 is critically involved in allergic eosinophilic airway inflammation.","date":"2007","source":"American journal of respiratory and critical care medicine","url":"https://pubmed.ncbi.nlm.nih.gov/17290046","citation_count":40,"is_preprint":false},{"pmid":"22098460","id":"PMC_22098460","title":"CD48 as a novel molecular target for antibody therapy in multiple myeloma.","date":"2011","source":"British journal of haematology","url":"https://pubmed.ncbi.nlm.nih.gov/22098460","citation_count":40,"is_preprint":false},{"pmid":"24726403","id":"PMC_24726403","title":"Hippocampal vulnerability and subacute response following varied blast magnitudes.","date":"2014","source":"Neuroscience letters","url":"https://pubmed.ncbi.nlm.nih.gov/24726403","citation_count":40,"is_preprint":false},{"pmid":"30227150","id":"PMC_30227150","title":"Blast-induced \"PTSD\": Evidence from an animal model.","date":"2018","source":"Neuropharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/30227150","citation_count":37,"is_preprint":false},{"pmid":"17993672","id":"PMC_17993672","title":"BLAST QuickStart: example-driven web-based BLAST tutorial.","date":"2007","source":"Methods in molecular biology (Clifton, N.J.)","url":"https://pubmed.ncbi.nlm.nih.gov/17993672","citation_count":37,"is_preprint":false},{"pmid":"25472427","id":"PMC_25472427","title":"Exacerbation of blast-induced ocular trauma by an immune response.","date":"2014","source":"Journal of neuroinflammation","url":"https://pubmed.ncbi.nlm.nih.gov/25472427","citation_count":37,"is_preprint":false},{"pmid":"25255823","id":"PMC_25255823","title":"The CD48 receptor mediates Staphylococcus aureus human and murine eosinophil activation.","date":"2014","source":"Clinical and experimental allergy : journal of the British Society for Allergy and Clinical Immunology","url":"https://pubmed.ncbi.nlm.nih.gov/25255823","citation_count":35,"is_preprint":false},{"pmid":"26467468","id":"PMC_26467468","title":"OsGF14b Positively Regulates Panicle Blast Resistance but Negatively Regulates Leaf Blast Resistance in Rice.","date":"2015","source":"Molecular plant-microbe interactions : MPMI","url":"https://pubmed.ncbi.nlm.nih.gov/26467468","citation_count":35,"is_preprint":false},{"pmid":"7797269","id":"PMC_7797269","title":"Physical and genetic linkage of the genes encoding Ly-9 and CD48 on mouse and human chromosomes 1.","date":"1995","source":"Immunogenetics","url":"https://pubmed.ncbi.nlm.nih.gov/7797269","citation_count":34,"is_preprint":false},{"pmid":"16081768","id":"PMC_16081768","title":"2B4/CD48-mediated regulation of lymphocyte activation and function.","date":"2005","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/16081768","citation_count":34,"is_preprint":false},{"pmid":"16304379","id":"PMC_16304379","title":"Pathobiology of lymphoid and myeloid blast crisis and management issues.","date":"2005","source":"Hematology. American Society of Hematology. Education Program","url":"https://pubmed.ncbi.nlm.nih.gov/16304379","citation_count":34,"is_preprint":false},{"pmid":"34570416","id":"PMC_34570416","title":"Tangeretin inhibits fungal ferroptosis to suppress rice blast.","date":"2021","source":"Journal of integrative plant biology","url":"https://pubmed.ncbi.nlm.nih.gov/34570416","citation_count":34,"is_preprint":false},{"pmid":"25820172","id":"PMC_25820172","title":"Confirmation of Pig-a mutation in flow cytometry-identified CD48-deficient T-lymphocytes from F344 rats.","date":"2015","source":"Mutagenesis","url":"https://pubmed.ncbi.nlm.nih.gov/25820172","citation_count":32,"is_preprint":false},{"pmid":"35921533","id":"PMC_35921533","title":"Genome-wide CRISPR screens identify CD48 defining susceptibility to NK cytotoxicity in peripheral T-cell lymphomas.","date":"2022","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/35921533","citation_count":29,"is_preprint":false},{"pmid":"35095749","id":"PMC_35095749","title":"Perspectives on Primary Blast Injury of the Brain: Translational Insights Into Non-inertial Low-Intensity Blast Injury.","date":"2022","source":"Frontiers in neurology","url":"https://pubmed.ncbi.nlm.nih.gov/35095749","citation_count":29,"is_preprint":false},{"pmid":"38355622","id":"PMC_38355622","title":"Epigenetic regulation of CD38/CD48 by KDM6A mediates NK cell response in multiple myeloma.","date":"2024","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/38355622","citation_count":28,"is_preprint":false},{"pmid":"16803907","id":"PMC_16803907","title":"Crystal structure and binding properties of the CD2 and CD244 (2B4)-binding protein, CD48.","date":"2006","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/16803907","citation_count":28,"is_preprint":false},{"pmid":"16472597","id":"PMC_16472597","title":"CD48 controls T-cell and antigen-presenting cell functions in experimental colitis.","date":"2006","source":"Gastroenterology","url":"https://pubmed.ncbi.nlm.nih.gov/16472597","citation_count":27,"is_preprint":false},{"pmid":"27859399","id":"PMC_27859399","title":"CD48 on blood leukocytes and in serum of asthma patients varies with severity.","date":"2016","source":"Allergy","url":"https://pubmed.ncbi.nlm.nih.gov/27859399","citation_count":25,"is_preprint":false},{"pmid":"31922199","id":"PMC_31922199","title":"Acute myeloid leukemia immune escape by epigenetic CD48 silencing.","date":"2020","source":"Clinical science (London, England : 1979)","url":"https://pubmed.ncbi.nlm.nih.gov/31922199","citation_count":25,"is_preprint":false},{"pmid":"16148114","id":"PMC_16148114","title":"Distinctive lack of CD48 expression in subsets of human dendritic cells tunes NK cell activation.","date":"2005","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/16148114","citation_count":25,"is_preprint":false},{"pmid":"26232681","id":"PMC_26232681","title":"Blast induced neurotrauma causes overpressure dependent changes to the DNA methylation equilibrium.","date":"2015","source":"Neuroscience letters","url":"https://pubmed.ncbi.nlm.nih.gov/26232681","citation_count":25,"is_preprint":false},{"pmid":"31363034","id":"PMC_31363034","title":"Cellular Dynamics and Genomic Identity of Centromeres in Cereal Blast Fungus.","date":"2019","source":"mBio","url":"https://pubmed.ncbi.nlm.nih.gov/31363034","citation_count":24,"is_preprint":false},{"pmid":"20363967","id":"PMC_20363967","title":"SHIP influences signals from CD48 and MHC class I ligands that regulate NK cell homeostasis, effector function, and repertoire formation.","date":"2010","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/20363967","citation_count":24,"is_preprint":false},{"pmid":"34889372","id":"PMC_34889372","title":"Blast and accelerated phase CML: room for improvement.","date":"2021","source":"Hematology. American Society of Hematology. Education Program","url":"https://pubmed.ncbi.nlm.nih.gov/34889372","citation_count":24,"is_preprint":false},{"pmid":"35181171","id":"PMC_35181171","title":"Review of blast noise and the auditory system.","date":"2022","source":"Hearing research","url":"https://pubmed.ncbi.nlm.nih.gov/35181171","citation_count":23,"is_preprint":false},{"pmid":"31598627","id":"PMC_31598627","title":"Blast Preconditioning Protects Retinal Ganglion Cells and Reveals Targets for Prevention of Neurodegeneration Following Blast-Mediated Traumatic Brian Injury.","date":"2019","source":"Investigative ophthalmology & visual science","url":"https://pubmed.ncbi.nlm.nih.gov/31598627","citation_count":23,"is_preprint":false},{"pmid":"21561736","id":"PMC_21561736","title":"The SLAM family member CD48 (Slamf2) protects lupus-prone mice from autoimmune nephritis.","date":"2011","source":"Journal of autoimmunity","url":"https://pubmed.ncbi.nlm.nih.gov/21561736","citation_count":22,"is_preprint":false},{"pmid":"16002700","id":"PMC_16002700","title":"Mutational analysis of the human 2B4 (CD244)/CD48 interaction: Lys68 and Glu70 in the V domain of 2B4 are critical for CD48 binding and functional activation of NK cells.","date":"2005","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/16002700","citation_count":22,"is_preprint":false},{"pmid":"9188168","id":"PMC_9188168","title":"Characterisation of the low affinity interaction between rat cell adhesion molecules CD2 and CD48 by analytical ultracentrifugation.","date":"1997","source":"European biophysics journal : EBJ","url":"https://pubmed.ncbi.nlm.nih.gov/9188168","citation_count":22,"is_preprint":false},{"pmid":"24505299","id":"PMC_24505299","title":"HTLV-1 specific CD8+ T cell function augmented by blockade of 2B4/CD48 interaction in HTLV-1 infection.","date":"2014","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/24505299","citation_count":22,"is_preprint":false},{"pmid":"21278219","id":"PMC_21278219","title":"Auto-antibody production and glomerulonephritis in congenic Slamf1-/- and Slamf2-/- [B6.129] but not in Slamf1-/- and Slamf2-/- [BALB/c.129] mice.","date":"2011","source":"International immunology","url":"https://pubmed.ncbi.nlm.nih.gov/21278219","citation_count":21,"is_preprint":false},{"pmid":"38653755","id":"PMC_38653755","title":"Phytoalexin sakuranetin attenuates endocytosis and enhances resistance to rice blast.","date":"2024","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/38653755","citation_count":21,"is_preprint":false},{"pmid":"29867715","id":"PMC_29867715","title":"Vestibular Injury After Low-Intensity Blast Exposure.","date":"2018","source":"Frontiers in neurology","url":"https://pubmed.ncbi.nlm.nih.gov/29867715","citation_count":21,"is_preprint":false},{"pmid":"33893374","id":"PMC_33893374","title":"NK1 antagonists attenuate tau phosphorylation after blast and repeated concussive injury.","date":"2021","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/33893374","citation_count":21,"is_preprint":false},{"pmid":"8929458","id":"PMC_8929458","title":"CD48 delivers an accessory signal for CD40-mediated activation of human B cells.","date":"1996","source":"Cellular immunology","url":"https://pubmed.ncbi.nlm.nih.gov/8929458","citation_count":21,"is_preprint":false},{"pmid":"1655899","id":"PMC_1655899","title":"Further evidence for a gamma/delta T cell receptor-mediated TCT.1/CD48 recognition.","date":"1991","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/1655899","citation_count":21,"is_preprint":false},{"pmid":"9862369","id":"PMC_9862369","title":"Enhanced murine CD4+ T cell responses induced by the CD2 ligand CD48.","date":"1998","source":"European journal of immunology","url":"https://pubmed.ncbi.nlm.nih.gov/9862369","citation_count":20,"is_preprint":false},{"pmid":"12356317","id":"PMC_12356317","title":"Direct measurements of heterotypic adhesion between the cell surface proteins CD2 and CD48.","date":"2002","source":"Biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/12356317","citation_count":20,"is_preprint":false},{"pmid":"32898222","id":"PMC_32898222","title":"SMI-BLAST: a novel supervised search framework based on PSI-BLAST for protein remote homology detection.","date":"2021","source":"Bioinformatics (Oxford, England)","url":"https://pubmed.ncbi.nlm.nih.gov/32898222","citation_count":19,"is_preprint":false},{"pmid":"33219153","id":"PMC_33219153","title":"Human innate lymphoid cell precursors express CD48 that modulates ILC differentiation through 2B4 signaling.","date":"2020","source":"Science immunology","url":"https://pubmed.ncbi.nlm.nih.gov/33219153","citation_count":19,"is_preprint":false},{"pmid":"23349097","id":"PMC_23349097","title":"Toward a \"structural BLAST\": using structural relationships to infer function.","date":"2013","source":"Protein science : a publication of the Protein Society","url":"https://pubmed.ncbi.nlm.nih.gov/23349097","citation_count":19,"is_preprint":false},{"pmid":"27249817","id":"PMC_27249817","title":"Modulation of natural killer cell functions by interactions between 2B4 and CD48 in cis and in trans.","date":"2016","source":"Open biology","url":"https://pubmed.ncbi.nlm.nih.gov/27249817","citation_count":19,"is_preprint":false},{"pmid":"28626499","id":"PMC_28626499","title":"The Effects of Blast Exposure on Protein Deimination in the Brain.","date":"2017","source":"Oxidative medicine and cellular longevity","url":"https://pubmed.ncbi.nlm.nih.gov/28626499","citation_count":19,"is_preprint":false},{"pmid":"9041467","id":"PMC_9041467","title":"Both human alpha/beta and gamma interferons upregulate the expression of CD48 cell surface molecules.","date":"1997","source":"Journal of interferon & cytokine research : the official journal of the International Society for Interferon and Cytokine Research","url":"https://pubmed.ncbi.nlm.nih.gov/9041467","citation_count":19,"is_preprint":false},{"pmid":"30947296","id":"PMC_30947296","title":"Subversion of natural killer cell responses by a cytomegalovirus-encoded soluble CD48 decoy receptor.","date":"2019","source":"PLoS pathogens","url":"https://pubmed.ncbi.nlm.nih.gov/30947296","citation_count":17,"is_preprint":false},{"pmid":"38081865","id":"PMC_38081865","title":"Is Protein BLAST a thing of the past?","date":"2023","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/38081865","citation_count":17,"is_preprint":false},{"pmid":"24670806","id":"PMC_24670806","title":"Engagement of SLAMF2/CD48 prolongs the time frame of effective T cell activation by supporting mature dendritic cell survival.","date":"2014","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/24670806","citation_count":17,"is_preprint":false},{"pmid":"34083587","id":"PMC_34083587","title":"Axonopathy precedes cell death in ocular damage mediated by blast exposure.","date":"2021","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/34083587","citation_count":17,"is_preprint":false},{"pmid":"16109603","id":"PMC_16109603","title":"Clinical implications of blast immunophenotypes in myelodysplastic syndromes.","date":"2005","source":"Leukemia & lymphoma","url":"https://pubmed.ncbi.nlm.nih.gov/16109603","citation_count":17,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":45280,"output_tokens":8195,"usd":0.129383,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":18012,"output_tokens":4379,"usd":0.099767,"stage2_stop_reason":"end_turn"},"total_usd":0.22915,"stage1_batch_id":"msgbatch_01ACAxJQabDsht39JXeWG22d","stage2_batch_id":"msgbatch_01QEU22A9U5sbPTgsMzTmvSf","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1992,\n      \"finding\": \"CD48 is the ligand (counter-receptor) for mouse CD2; identified by generating a chimeric CD2-IgG fusion protein that bound to CD48 on T cell lines, confirmed by protein microsequencing of the affinity-purified antigen, reactivity with recombinant CD48, and inhibition of CD2–CD48 binding by soluble CD48. CD48 is a GPI-anchored glycoprotein (~45 kD) predominantly expressed on hematopoietic cells.\",\n      \"method\": \"Chimeric CD2-IgG fusion protein pulldown, protein microsequencing, mAb inhibition assays, soluble recombinant protein competition\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — reciprocal binding assays with soluble proteins, protein microsequencing, mAb blocking, and functional T-cell activation assays in a single study\",\n      \"pmids\": [\"1383383\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1993,\n      \"finding\": \"Quantitative kinetic and affinity analysis of rat CD2–CD48 interaction by surface plasmon resonance (BIAcore) revealed a very low-affinity interaction (KD ~60–90 µM) driven by an extremely rapid off-rate (koff ≥ 6 s⁻¹), with a normal on-rate (kon ≥ 10⁵ M⁻¹s⁻¹). Glycosylation of CD2 had little effect on binding affinity.\",\n      \"method\": \"Surface plasmon resonance (BIAcore) with soluble recombinant proteins in both binding orientations\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — rigorous biophysical assay in both orientations with soluble proteins, replicated in complementary ultracentrifugation study (PMID:9188168)\",\n      \"pmids\": [\"7903240\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1995,\n      \"finding\": \"The CD2-binding site on rat CD48 lies on the GFCC'C'' beta-sheet of its membrane-distal Ig domain (equivalent to the CD2 ligand-binding surface). Complementary charged-residue mutations in CD48 and CD2 demonstrated direct electrostatic contacts between the two binding surfaces, establishing a head-to-head docking topology. The modeled CD2–CD48 complex spans ~134 Å, similar to the predicted TCR–pMHC complex distance.\",\n      \"method\": \"Complementary site-directed mutagenesis of CD48 and CD2, functional binding assays, molecular modelling\",\n      \"journal\": \"Current biology : CB\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — mutagenesis with complementary charge-swap pairs establishing direct contact residues, supported by modelling and later crystallographic confirmation\",\n      \"pmids\": [\"7697352\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1996,\n      \"finding\": \"NMR titration of ¹⁵N-labelled rat CD2 domain 1 with soluble CD48 identified the CD48-binding surface of CD2 as the GFCC'C'' face (~700–800 Ų), with no large-scale structural changes in CD2 upon CD48 binding. Species- and ligand-specific binding differences between rat and human CD2 are explained by as few as three residues (Thr37, Leu38, Glu41 in rat; Lys42, Lys43, Gln46 in human).\",\n      \"method\": \"Heteronuclear NMR (²D ¹⁵N-¹H HSQC) titration with soluble CD48\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — direct NMR mapping of binding surface with chemical shift perturbation analysis, consistent with mutagenesis data\",\n      \"pmids\": [\"8634239\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"Analytical ultracentrifugation (sedimentation equilibrium and velocity) in free solution confirmed the weak affinity of the rat CD2–CD48 interaction (KD 20–110 µM at 5°C), ruling out significant self-association of either reactant as a confounding factor in SPR measurements.\",\n      \"method\": \"Analytical ultracentrifugation (sedimentation equilibrium and velocity)\",\n      \"journal\": \"European biophysics journal : EBJ\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — orthogonal biophysical method confirming SPR-derived affinity, single study\",\n      \"pmids\": [\"9188168\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"2B4 (CD244) is an additional ligand for CD48: recombinant mouse 2B4 extracellular domain bound to CD48-expressing cells and this binding was blocked by anti-CD48 mAbs. Surface plasmon resonance showed mCD48 binds m2B4 with 6–9-fold higher affinity (KD ~16 µM at 37°C) than it binds CD2; human CD48 bound human 2B4 with KD ~8 µM.\",\n      \"method\": \"Fluorescent bead binding assay with recombinant 2B4, anti-CD48 mAb blocking, surface plasmon resonance\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — direct binding assay plus quantitative SPR, replicated independently in same year (PMID:9834056)\",\n      \"pmids\": [\"9841922\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"CD48 fusion protein (CD48-IgG1) identified 2B4 as a novel counter-receptor of CD48 by immunofluorescence and immunoprecipitation, independently confirming the CD48–2B4 interaction.\",\n      \"method\": \"Chimeric CD48-IgG1 fusion protein pulldown, immunofluorescence, immunoprecipitation\",\n      \"journal\": \"Journal of immunology (Baltimore, Md. : 1950)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — two orthogonal binding methods, independent confirmation of PMID:9841922\",\n      \"pmids\": [\"9834056\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1990,\n      \"finding\": \"Mouse BCM1/CD48 (also known as OX45/Blast-1) is a GPI-anchored glycoprotein expressed on leukocytes, cloned and sequenced. Genomic linkage analysis placed the Bcm-1 locus on distal mouse chromosome 1, linked to an ATPase alpha chain gene, establishing CD48 as a member of the CD2/LFA3 Ig superfamily subgroup.\",\n      \"method\": \"cDNA cloning and sequencing, genetic linkage mapping, pulse-field gel electrophoresis\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — cDNA cloning with sequence analysis and genetic mapping; structural inference of GPI anchor\",\n      \"pmids\": [\"1693656\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1991,\n      \"finding\": \"CD48 (Blast-1) is expressed on T cells and monocytes in addition to B cells. EBV transformation and PMA/IL-4/PHA stimulation increase surface CD48 expression by elevating steady-state CD48 mRNA. A subset of CD48 molecules is resistant to GPI-specific phospholipase C digestion and may exist in a complexed form on the cell surface.\",\n      \"method\": \"Immunoprecipitation, immunofluorescence, Northern blot, GPI-PLC digestion, Cos-7 transfection\",\n      \"journal\": \"Journal of immunology (Baltimore, Md. : 1950)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — multiple biochemical and cellular methods in one study\",\n      \"pmids\": [\"1848579\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Engagement of 2B4 on human NK cells by anti-2B4 mAb or by CD48 (its ligand) triggers NK cell-mediated cytotoxicity. 2B4 is also expressed on monocytes and basophils, but 2B4 ligation does not activate T cells or monocytes, indicating cell-type-specific signaling downstream of the 2B4–CD48 interaction.\",\n      \"method\": \"Cytotoxicity assays using anti-2B4 mAb and recombinant CD48 protein, flow cytometry, molecular cloning of human 2B4\",\n      \"journal\": \"European journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — functional cytotoxicity assay with recombinant CD48 ligand, single laboratory\",\n      \"pmids\": [\"10359122\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"CD48-deficient mice (generated by gene targeting) display a profound defect in CD4⁺ T cell activation: proliferative responses to mitogens, anti-CD3 mAb, and alloantigen are all reduced. CD48 is required on both T cells and antigen-presenting cells. The most dramatic impairment occurs when highly purified T cells are stimulated through the TCR plus PMA, suggesting CD48 plays a role in TCR signaling.\",\n      \"method\": \"Gene targeting (knockout mice), co-culture proliferation assays, mitogen and alloantigen stimulation assays\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean genetic knockout with multiple functional readouts; CD48 requirement demonstrated on both T cells and APCs by cell mixing experiments\",\n      \"pmids\": [\"9927686\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"NAIL (human 2B4 homologue, later NTB-A) binds CD48 as its counter-receptor. Recombinant CD48 protein enhances NK cell cytotoxicity and induces IFN-γ production. Soluble NAIL-Fc stimulates B cell proliferation and DC IL-12/TNF-α release, demonstrating that CD48–NAIL/2B4 interactions regulate multiple immune cell responses.\",\n      \"method\": \"Soluble fusion protein binding assays, NK cytotoxicity assays, IFN-γ ELISA, B cell proliferation, DC cytokine assays\",\n      \"journal\": \"European journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — multiple functional assays with recombinant CD48, single laboratory\",\n      \"pmids\": [\"10556801\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"CD48 co-clusters with IL-2Rα and HLA molecules in cholesterol-dependent lipid raft microdomains (~600–800 nm clusters) on T lymphoma cells. Disruption of membrane cholesterol with filipin or methyl-β-cyclodextrin disperses these clusters, whereas the transferrin receptor (non-raft) clusters are largely unaffected and do not co-localize with CD48.\",\n      \"method\": \"Immunogold staining/electron microscopy, confocal microscopy, cholesterol depletion, crosscorrelation analysis\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — two imaging modalities with cholesterol-depletion perturbation; single study\",\n      \"pmids\": [\"10823948\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Direct force measurements using surface force apparatus confirmed that the full-length extracellular domains of CD2 and CD48 adhere in a head-to-head orientation, with no long-range electrostatic attraction, abrupt adhesive failure (no partial unfolding), and weak adhesion requiring lateral receptor mobility. This is the first direct measurement of forces governing CD2–CD48 heterotypic adhesion.\",\n      \"method\": \"Direct surface force measurements between protein-coated lipid bilayers\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — unique biophysical reconstitution method, single study, single laboratory\",\n      \"pmids\": [\"12356317\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"CD48 on mast cells aggregates at sites of Mycobacterium tuberculosis binding, and anti-CD48 antibodies inhibit histamine release triggered by mycobacteria, implicating CD48 as a receptor mediating mast cell recognition of and activation by M. tuberculosis.\",\n      \"method\": \"Confocal microscopy of CD48 aggregation at bacterial binding sites, anti-CD48 mAb inhibition of histamine release\",\n      \"journal\": \"Journal of immunology (Baltimore, Md. : 1950)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — two orthogonal approaches (localization + functional inhibition), single study\",\n      \"pmids\": [\"12759438\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Homotypic 2B4/CD48 interactions among NK cells are essential for IL-2-driven NK cell expansion, cytotoxicity, and IFN-γ secretion; CD2/CD48 interactions on NK cells are not required for these functions. 2B4-deficient but not CD2-deficient NK cells fail to clear syngeneic tumor cells in vivo. Defective 2B4/CD48 signaling correlates with impaired calcium signaling. GFP-tagged 2B4 localizes specifically to NK–NK conjugation sites, confirming homotypic trans-interaction.\",\n      \"method\": \"Gene-deficient NK cells (2B4⁻/⁻, CD48⁻/⁻), cytotoxicity assays, IFN-γ ELISA, calcium imaging, GFP-2B4 live-cell imaging, in vivo tumor clearance\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods including KO mice, live imaging, signaling assays, and in vivo tumor model\",\n      \"pmids\": [\"15905190\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Site-directed mutagenesis of human 2B4 identified Lys68 and Glu70 in the V domain as critical residues for CD48 binding and for 2B4-mediated functional activation of human NK cells; double Lys68Ala/Glu70Ala mutant abolishes CD48-Fc binding and NK activation.\",\n      \"method\": \"Site-directed mutagenesis, flow cytometry binding assay with CD48-Fc fusion protein, NK cell functional activation assay\",\n      \"journal\": \"Journal of immunology (Baltimore, Md. : 1950)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — mutagenesis with defined functional readout, single laboratory\",\n      \"pmids\": [\"16002700\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Crystal structure of the receptor-binding domain of rat CD48 resolved. The receptor-binding surface is unusually flat and electrostatically complementary to CD2. Thermodynamic analysis showed CD48–CD2 binding is driven by equivalent weak enthalpic and entropic contributions, distinct from the human CD2–CD58 interaction (which has a large entropic barrier). The flat, charge-complementary topology explains why CD48 can cross-react with both CD2 and 2B4/CD244.\",\n      \"method\": \"X-ray crystallography, isothermal titration calorimetry/thermodynamic binding analysis, comparative structural modelling\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure combined with quantitative thermodynamic analysis in a single study\",\n      \"pmids\": [\"16803907\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"CD48 is an IL-3-inducible activating receptor on human eosinophils; cross-linking CD48 triggers release of eosinophil granule proteins (degranulation). In a murine asthma model, CD48 expression is induced by allergen challenge and partially regulated by IL-3; anti-IL-3 reduces both CD48 expression and airway inflammation.\",\n      \"method\": \"Flow cytometry, antibody cross-linking degranulation assays, murine OVA asthma model, anti-IL-3 antibody treatment\",\n      \"journal\": \"Journal of immunology (Baltimore, Md. : 1950)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — in vitro cross-linking assay plus in vivo mouse model, single laboratory\",\n      \"pmids\": [\"16785501\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"CD48 controls both T cell and APC function in experimental colitis. CD48⁻/⁻ CD4⁺ T cells fail to induce colitis when transferred into CD48⁻/⁻ × Rag-2⁻/⁻ recipients (but can into Rag-2⁻/⁻ hosts), indicating CD48 is required on APCs in the recipient to drive disease. CD48⁻/⁻ macrophages produce less TNF-α and IL-12 upon LPS stimulation and show defective bacterial clearance. Anti-CD48 mAb treatment ameliorates colitis even after disease onset.\",\n      \"method\": \"Adoptive transfer colitis model using CD48⁻/⁻ and Rag-2⁻/⁻ mice, in vitro macrophage stimulation assays, anti-CD48 therapeutic treatment\",\n      \"journal\": \"Gastroenterology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean KO genetics, cell-transfer epistasis, multiple in vitro functional assays, therapeutic intervention\",\n      \"pmids\": [\"16472597\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"GPI-anchored CD48 (but not CD59) is recruited to the immobilized TCR/CD3 complex upon T cell activation. CD48 reorganization is required for LAT association with the TCR/CD3 complex and for IL-2 production. CD2 acts upstream of CD48: CD2 associates with TCR/CD3 independently of CD48 and recruits Lck, while CD48 recruitment and subsequent LAT association depend on CD2. Thus CD2 and CD48 cooperate hierarchically to build the early TCR signalosome.\",\n      \"method\": \"Co-immunoprecipitation, proximity ligation/signalosome reconstitution assays, CD48 knockdown/knockout T cells, IL-2 ELISA, LAT co-precipitation\",\n      \"journal\": \"Journal of immunology (Baltimore, Md. : 1950)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP establishing hierarchical pathway placement, CD48-specific siRNA knockdown plus KO confirmation, multiple signaling readouts\",\n      \"pmids\": [\"19494291\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"Both type I (α/β) and type II (γ) interferons upregulate CD48 mRNA and surface protein expression on multiple human cell lines and peripheral blood CD3⁺, CD14⁺, and CD19⁺ subsets; IFN has no corresponding effect on LFA-3 expression.\",\n      \"method\": \"Northern blot, flow cytometry, IFN treatment of human cell lines and PBMCs\",\n      \"journal\": \"Journal of interferon & cytokine research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — two orthogonal methods (mRNA and protein), multiple cell types examined, single laboratory\",\n      \"pmids\": [\"9041467\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"ORMDL3, an ER-localized protein, regulates IL-3-induced CD48 expression on eosinophils and mediates CD48-dependent eosinophil degranulation; ORMDL3 knockdown significantly inhibits eosinophil degranulation and in vivo recruitment.\",\n      \"method\": \"ORMDL3 overexpression and siRNA knockdown in eosinophils, flow cytometry, in vivo murine asthma model, degranulation assays\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — gain- and loss-of-function with in vivo confirmation, single laboratory\",\n      \"pmids\": [\"24056518\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"CD48 on human and murine eosinophils serves as a receptor mediating Staphylococcus aureus and its exotoxins (SEB, protein A, peptidoglycan) activation: SA/exotoxins physically bind to CD48, cause eosinophil degranulation, cytokine release, and signal transduction; these effects are significantly reduced by CD48 blocking or in CD48⁻/⁻ bone marrow eosinophils. In vivo, CD48⁻/⁻ mice show reduced eosinophil recruitment in SEB-induced peritonitis.\",\n      \"method\": \"Confocal microscopy of SA binding to CD48, adhesion and degranulation assays, cytokine ELISA, CD48⁻/⁻ mouse peritonitis model\",\n      \"journal\": \"Clinical and experimental allergy\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — physical interaction shown by microscopy, multiple functional readouts, KO confirmation both in vitro and in vivo\",\n      \"pmids\": [\"25255823\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Engagement of SLAMF2/CD48 on dendritic cells (DCs) by SLAMF4 recombinant protein or anti-SLAMF2 Ab activates immature DCs and prolongs survival of DNA-activated DCs by inhibiting IFN-β production and IFN-β-induced apoptosis, and by promoting production of the granzyme B inhibitor protease inhibitor-9.\",\n      \"method\": \"Anti-SLAMF2 mAb and recombinant SLAMF4 protein engagement of DCs, IFN-β ELISA, apoptosis assays, granzyme B inhibitor measurement\",\n      \"journal\": \"Journal of immunology (Baltimore, Md. : 1950)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — multiple functional endpoints but signaling mechanism inferred indirectly, single laboratory\",\n      \"pmids\": [\"24670806\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"2B4 on NK cells interacts with CD48 both in trans (on neighbouring cells) and in cis (on the same NK cell surface), using the same binding site. Cis interaction induces basal 2B4 phosphorylation but reduces trans-binding to CD48-positive target cells; interfering with cis interaction enhanced lysis of CD48-expressing tumour cells.\",\n      \"method\": \"Proximity ligation assay, FRET, anti-2B4 blocking to perturb cis interaction, cytotoxicity assays\",\n      \"journal\": \"Open biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — multiple biochemical and functional assays demonstrating cis interaction, single laboratory\",\n      \"pmids\": [\"27249817\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"A cytomegalovirus-encoded soluble CD48 homologue (A43, encoded by owl monkey CMV) is secreted after proteolytic processing and binds human 2B4 with high affinity and slow dissociation rate (SPR). A43 abrogates host CD48:2B4 interactions, reduces NK–target conjugate formation and immunological synapse establishment, and impairs 2B4-mediated cytotoxicity and IFN-γ production by NK cells.\",\n      \"method\": \"Surface plasmon resonance, NK cell cytotoxicity assays, conjugate formation assays, immunological synapse imaging, IFN-γ ELISA\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — quantitative SPR plus multiple orthogonal functional assays, mechanistically establishes CD48–2B4 axis as viral immune evasion target\",\n      \"pmids\": [\"30947296\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"CD48 expression in AML cells is epigenetically regulated by DNA methylation; treatment with a hypomethylating agent increases CD48 expression on AML cells and enhances NK cell killing of AML cells in vitro. Restoration of CD48 expression reverses AML immune evasion and activates NK cell function in vivo.\",\n      \"method\": \"Methylation analysis, hypomethylating agent treatment, NK cytotoxicity assays in vitro and in vivo mouse model\",\n      \"journal\": \"Clinical science (London, England : 1979)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — epigenetic mechanism demonstrated with functional NK killing readout, in vivo confirmation, single laboratory\",\n      \"pmids\": [\"31922199\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Human innate lymphoid cell precursors (ILCPs) express CD48, and the interaction of 2B4 (on NKPs) with CD48 (on ILCPs) promotes differentiation of ILC2s; 2B4–CD48 signaling modulates ILC lineage commitment.\",\n      \"method\": \"Flow cytometry of precursor subsets, in vitro differentiation assays, in vivo humanized mouse model\",\n      \"journal\": \"Science immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — defined precursor subsets with functional differentiation assay and in vivo confirmation, single laboratory\",\n      \"pmids\": [\"33219153\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"GDF15 binds CD48 as a previously unrecognized receptor on T cells, thereby downregulating STUB1 (an E3 ubiquitin ligase that mediates FOXP3 degradation), which promotes generation of peripheral iTreg cells and enhances suppressive function of nTreg cells; GDF15 neutralizing antibody eradicates HCC in mouse models.\",\n      \"method\": \"Co-immunoprecipitation, mass spectrometry, RNA sequencing, ChIP, flow cytometry (CyTOF), GDF15-knockout HCC mouse model, hybridoma-generated neutralizing mAb\",\n      \"journal\": \"Journal for immunotherapy of cancer\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP and mass spec identification of CD48 as GDF15 receptor with multiple downstream mechanistic assays, single laboratory; novel finding not yet independently replicated\",\n      \"pmids\": [\"34489334\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Genome-wide CRISPR screens in ATLL cell lines identified CD48 as the top gene whose knockout confers resistance to NK-cell-mediated cytotoxicity; CD48-knockout ATLL cells evade NK-cell effector function (reduced IFN-γ induction and degranulation by primary human NK cells). Primary ATLL cells show reduced CD48 expression with disease progression.\",\n      \"method\": \"Genome-wide CRISPR knockout screen, flow cytometry, NK cytotoxicity assays with primary human NK cells\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — unbiased genome-wide screen confirmed with primary human NK cells and primary patient samples, two cell lines tested\",\n      \"pmids\": [\"35921533\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"KDM6A loss leads to increased H3K27me3 on the CD48 promoter, causing CD48 downregulation in multiple myeloma cells. EZH2 inhibitor treatment restores CD48 (and CD38) expression and reverses resistance to Daratumumab-mediated ADCC, establishing KDM6A/EZH2/H3K27me3 as an epigenetic axis regulating CD48 expression.\",\n      \"method\": \"Genome-wide CRISPR screens, ChIP for H3K27me3 on CD48 promoter, EZH2 inhibitor treatment, CD38/CD48 re-expression, ADCC assays\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — CRISPR screen plus ChIP mechanistic validation plus pharmacological rescue, two orthogonal KDM6A-loss models\",\n      \"pmids\": [\"38355622\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"CD48 is a GPI-anchored Ig-superfamily glycoprotein expressed broadly on hematopoietic cells that functions as an adhesion and co-stimulatory ligand: it binds CD2 with very low affinity (KD ~60–90 µM, head-to-head via GFCC'C'' beta-sheet surfaces as resolved by mutagenesis, NMR, and X-ray crystallography) and binds its high-affinity ligand 2B4/CD244 (KD ~8–16 µM), thereby co-stimulating T cell activation (by recruiting LAT to the TCR/CD3 signalosome downstream of CD2/Lck), regulating NK cell cytotoxicity and IFN-γ production (including through homotypic NK–NK 2B4/CD48 interactions), activating eosinophils and mast cells (including in response to bacterial pathogens such as M. tuberculosis and S. aureus), and modulating DC survival; CD48 expression is upregulated by interferons and IL-3 and is epigenetically repressed by EZH2/H3K27me3 (controlled by KDM6A), and CD48 has additionally been identified as a receptor for GDF15 on Treg cells linking tumor-derived signals to immunosuppression.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"CD48 is a GPI-anchored Ig-superfamily glycoprotein expressed broadly on hematopoietic cells that functions as a heterotypic adhesion and co-stimulatory ligand coordinating T cell, NK cell, and innate immune responses [#0, #7]. It engages CD2 as a counter-receptor through a very low-affinity, fast-dissociating interaction (KD ~60–90 µM) mediated by the GFCC'C'' beta-sheet face of its membrane-distal Ig domain in a head-to-head docking topology, a binding mode confirmed biophysically and crystallographically as an unusually flat, charge-complementary surface [#0, #1, #2, #17]. The same flat surface allows CD48 to cross-react with its higher-affinity ligand 2B4/CD244 (KD ~8–16 µM), and these CD48–2B4 interactions—including homotypic NK–NK engagement—drive NK cell cytotoxicity and IFN-γ production [#5, #15, #17]. In T cells, GPI-anchored CD48 is recruited to the immobilized TCR/CD3 complex downstream of CD2/Lck and is required for LAT association and IL-2 production, placing CD48 in a hierarchical co-stimulatory pathway that builds the early TCR signalosome [#10, #20]. Beyond lymphocytes, CD48 acts as an activating receptor on eosinophils and mast cells, mediating recognition of bacterial pathogens including M. tuberculosis and S. aureus and triggering degranulation [#14, #18, #23]. CD48 surface expression is induced by type I/II interferons and IL-3 and is epigenetically repressed via H3K27me3 deposition on its promoter, an axis controlled by KDM6A/EZH2 and by DNA methylation that tumors exploit to evade NK-mediated killing [#18, #21, #30, #31]. CD48 has additionally been identified as a receptor for GDF15 on T cells, linking tumor-derived signals to Treg-mediated immunosuppression [#29].\",\n  \"teleology\": [\n    {\n      \"year\": 1990,\n      \"claim\": \"Establishing CD48 as a cloned GPI-anchored leukocyte glycoprotein of the CD2/LFA3 Ig superfamily subgroup defined the molecular identity from which all functional studies proceeded.\",\n      \"evidence\": \"cDNA cloning, sequencing, and genetic linkage mapping of mouse BCM1/CD48\",\n      \"pmids\": [\"1693656\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"GPI anchor inferred structurally rather than directly demonstrated\", \"no ligand or function assigned at this stage\"]\n    },\n    {\n      \"year\": 1992,\n      \"claim\": \"Identifying CD48 as the counter-receptor for CD2 answered what physiological ligand engages this molecule and connected it to T cell adhesion.\",\n      \"evidence\": \"Chimeric CD2-IgG pulldown, protein microsequencing, and mAb blocking in T cell lines\",\n      \"pmids\": [\"1383383\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"affinity and kinetics of the interaction not quantified\", \"binding interface not mapped\"]\n    },\n    {\n      \"year\": 1993,\n      \"claim\": \"Quantitative SPR established that CD2–CD48 is an extremely low-affinity, fast-off-rate interaction, defining the biophysical regime of cell-surface adhesion-receptor recognition.\",\n      \"evidence\": \"Surface plasmon resonance with soluble recombinant proteins in both orientations; confirmed by analytical ultracentrifugation\",\n      \"pmids\": [\"7903240\", \"9188168\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"does not explain how weak affinity is translated into productive signaling\", \"structural basis of binding not resolved\"]\n    },\n    {\n      \"year\": 1996,\n      \"claim\": \"Mapping the binding surface to the GFCC'C'' beta-sheet face on both CD48 and CD2 established the head-to-head docking topology and the structural origin of species specificity.\",\n      \"evidence\": \"Complementary charge-swap mutagenesis, heteronuclear NMR titration, and molecular modelling\",\n      \"pmids\": [\"7697352\", \"8634239\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"high-resolution crystal structure not yet available\", \"thermodynamic basis of recognition not determined\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Identifying 2B4/CD244 as a second, higher-affinity ligand revealed that CD48 functions in more than one receptor axis and engages activating receptors beyond CD2.\",\n      \"evidence\": \"Recombinant 2B4 binding assays, anti-CD48 blocking, and SPR; independent CD48-IgG1 pulldown confirmation\",\n      \"pmids\": [\"9841922\", \"9834056\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"downstream signaling of the 2B4–CD48 interaction not yet defined\", \"relative physiological role of CD2 vs 2B4 engagement unclear\"]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Genetic knockout demonstrated that CD48 is functionally required on both T cells and APCs for CD4+ T cell activation, and that CD48–2B4 engagement controls NK cytotoxicity and IFN-γ, moving CD48 from a binding partner to a causal regulator of immune function.\",\n      \"evidence\": \"CD48-deficient mice with proliferation/cell-mixing assays; NK cytotoxicity and IFN-γ assays with recombinant CD48 and NAIL/2B4 homologue\",\n      \"pmids\": [\"9927686\", \"10359122\", \"10556801\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"molecular mechanism linking GPI-anchored CD48 to TCR signaling not resolved\", \"signaling events downstream of CD48 in APCs unmapped\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Demonstrating that CD48 co-clusters with IL-2Rα and HLA in cholesterol-dependent lipid rafts provided a membrane-organization basis for how a GPI-anchored molecule participates in signaling.\",\n      \"evidence\": \"Immunogold/EM and confocal imaging with cholesterol depletion on T lymphoma cells\",\n      \"pmids\": [\"10823948\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"functional consequence of raft clustering for signaling not directly tested\", \"single cell type examined\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"The crystal structure plus thermodynamic analysis explained how an unusually flat, charge-complementary CD48 surface enables cross-reactivity with both CD2 and 2B4, resolving the structural logic of dual ligand recognition.\",\n      \"evidence\": \"X-ray crystallography of rat CD48 receptor-binding domain with isothermal titration calorimetry; surface force measurements of CD2–CD48 adhesion\",\n      \"pmids\": [\"16803907\", \"12356317\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"structure of the full CD48–2B4 complex not solved\", \"structures from rat domains rather than human\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Placing CD48 hierarchically downstream of CD2/Lck and upstream of LAT recruitment defined the mechanistic logic by which CD2 and CD48 cooperate to assemble the early TCR signalosome.\",\n      \"evidence\": \"Reciprocal Co-IP, CD48 knockdown/knockout T cells, LAT co-precipitation, and IL-2 readouts\",\n      \"pmids\": [\"19494291\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"how a GPI-anchored protein lacking a cytoplasmic tail transmits the signal not fully explained\", \"physical link between CD48 and LAT not identified\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Establishing CD48 as a receptor for whole bacteria and exotoxins on eosinophils and mast cells, and as a survival-modulating receptor on DCs, broadened CD48 function from lymphocyte co-stimulation to innate pathogen sensing and myeloid regulation.\",\n      \"evidence\": \"M. tuberculosis and S. aureus binding/degranulation assays with anti-CD48 blocking and CD48−/− eosinophils; SLAMF4/anti-SLAMF2 engagement of DCs\",\n      \"pmids\": [\"12759438\", \"16785501\", \"25255823\", \"24670806\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"molecular details of bacterial ligand binding to CD48 not defined\", \"signaling pathway from CD48 to degranulation unresolved\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Defining IFN-, IL-3-, DNA-methylation- and KDM6A/EZH2-dependent control of CD48 surface expression established how CD48 levels are tuned and how tumors silence CD48 to escape NK-mediated and antibody-dependent killing.\",\n      \"evidence\": \"IFN/IL-3 induction assays; ORMDL3 manipulation; methylation and H3K27me3 ChIP with hypomethylating and EZH2-inhibitor rescue and NK/ADCC readouts in AML and myeloma\",\n      \"pmids\": [\"9041467\", \"16785501\", \"24056518\", \"31922199\", \"38355622\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"transcription factors directly driving CD48 from these signals not fully defined\", \"relative contribution of DNA methylation vs H3K27me3 across tumor types unclear\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Identifying CD48 as a receptor for GDF15 on T cells linked tumor-derived signals to Treg-mediated immunosuppression via STUB1/FOXP3, expanding CD48's ligand repertoire beyond Ig-superfamily counter-receptors.\",\n      \"evidence\": \"Co-IP/mass spectrometry receptor identification with downstream RNA-seq, ChIP, CyTOF and a GDF15-KO HCC model\",\n      \"pmids\": [\"34489334\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"GDF15–CD48 binding not independently replicated\", \"structural basis of GDF15 engagement of CD48 unknown\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Unbiased CRISPR screens nominated CD48 as the dominant determinant of tumor susceptibility to NK-cell killing, cementing the CD48–2B4 axis as a clinically relevant immune-evasion target.\",\n      \"evidence\": \"Genome-wide CRISPR knockout screens in ATLL lines with primary human NK cytotoxicity assays and patient samples\",\n      \"pmids\": [\"35921533\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"mechanism of CD48 loss in primary disease progression not defined\", \"interplay between CD48 and other NK ligands not addressed\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How a cytoplasmic-tail-less GPI-anchored CD48 physically transduces signals into the TCR signalosome and into innate effector pathways, and whether the GDF15–CD48 axis generalizes, remain open.\",\n      \"evidence\": null,\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"no defined cytoplasmic transducer for GPI-anchored CD48\", \"GDF15–CD48 interaction awaits independent confirmation\", \"no human-protein high-resolution structure of CD48–2B4 or CD48–GDF15 complexes\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0048018\", \"supporting_discovery_ids\": [0, 5, 11, 29]},\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [14, 18, 23]},\n      {\"term_id\": \"GO:0098631\", \"supporting_discovery_ids\": [0, 2, 13]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [7, 8, 12]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [10, 15, 20, 30]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [20, 29]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"CD2\", \"CD244\", \"GDF15\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}