The following list includes selected CD molecules that are referred to in the text. Many cytokines and cytokine receptors have been assigned CD numbers, but we refer to these by the more descriptive cytokine designation, and these are listed in Appendix II. A complete and up-to-date listing of CD molecules may be found at http://www.hcdm.org .
| CD Number (Other Names) | Molecular Structure, Family | Main Cellular Expression | Known or Proposed Function(s) |
|---|---|---|---|
| CD1a–d | 49 kD; class I MHC-like Ig superfamily; β 2 -microglobulin associated | Thymocytes, dendritic cells (including Langerhans cells) | Presentation of nonpeptide (lipid and glycolipid) antigens to some T cells |
| CD1e | 28 kD; class I MHC-like; β2-microglobulin associated | Dendritic cells | Same as CD1a |
| CD2 (LFA-2) | 50 kD; Ig superfamily | T cells, NK cells | Adhesion molecule (binds CD58); T cell activation; cytotoxic T lymphocyte (CTL)– and natural killer (NK) cell–mediated lysis |
| CD3g (CD3γ) | 25–28 kD; associated with CD3δ and CD3ε in TCR complex; Ig superfamily; ITAM in cytoplasmic tail | T cells | Cell surface expression of and signal transduction by the T cell antigen receptor |
| CD3d (CD3δ) | 20 kD; associated with CD3γ and CD3ε in TCR complex; Ig superfamily; ITAM in cytoplasmic tail | T cells | Cell surface expression of and signal transduction by the T cell antigen receptor |
| CD3e (CD3ε) | 20 kD; associated with CD3δ and CD3γ in TCR complex; Ig superfamily; ITAM in cytoplasmic tail | T cells | Cell surface expression of and signal transduction by the T cell antigen receptor |
| CD4 | 55 kD; Ig superfamily | Class II MHC-restricted T cells; some macrophages | Coreceptor in class II MHC-restricted antigen-induced T cell activation (binds to class II MHC molecules); thymocyte development; receptor for HIV |
| CD5 | 67 kD; scavenger receptor family | T cells; B-1 B cell subset | Signaling molecule; binds CD72 |
| CD8a | 34 kD; expressed as a homodimer or heterodimer with CD8b chain | Class I MHC-restricted T cells; subset of dendritic cells | Coreceptor in class I MHC-restricted antigen-induced T cell activation (binds to class I MHC molecules); thymocyte development |
| CD8b | 34 kD; expressed as a heterodimer with CD8a chain Ig superfamily | Class I MHC-restricted T cells | Same as CD8α |
| CD10 | 100 kD; type II membrane protein | Immature and some mature B cells; lymphoid progenitors, granulocytes | Metalloproteinase; unknown function in the immune system |
| CD11a (LFA-1 α chain) | 180 kD; noncovalently linked to CD18 to form LFA-1 integrin | Leukocytes | Cell-cell adhesion; binds to ICAM-1 (CD54), ICAM-2 (CD102), and ICAM-3 (CD50) |
| CD11b (Mac-1; CR3) | 165 kD; noncovalently linked to CD18 to form Mac-1 integrin | Granulocytes, monocytes, macrophages, dendritic cells, NK cells | Phagocytosis of iC3b-coated particles; neutrophil and monocyte adhesion to endothelium (binds CD54) and extracellular matrix proteins |
| CD11c (p150,95; CR4α chain) | 145 kD; noncovalently linked to CD18 to form p150,95 integrin | Monocytes, macrophages, granulocytes, NK cells | Similar functions as CD11b |
| CD14 | 53 kD; GPI linked | Dendritic cells, monocytes, macrophages, granulocytes | Binds complex of LPS and LPS-binding protein and displays LPS to TLR4; required for LPS-induced macrophage activation |
| CD16a (FcγRIIIA) | 50–70 kD; transmembrane protein; Ig superfamily | NK cells, macrophages | Binds Fc region of IgG; phagocytosis and antibody-dependent cellular cytotoxicity |
| CD16b (FcγRIIIB) | 50–70 kD; GPI linked; Ig superfamily | Neutrophils | Binds Fc region of IgG; synergy with Fcγ RII in immune complex–mediated neutrophil activation |
| CD18 | 95 kD; noncovalently linked to CD11a, CD11b, or CD11c to form β 2 integrins | Leukocytes | See CD11a, CD11b, CD11c |
| CD19 | 95 kD; Ig superfamily | Most B cells | B cell activation; forms a coreceptor complex with CD21 and CD81 that delivers signals that synergize with signals from B cell antigen receptor complex |
| CD20 | 35–37 kD; tetraspan (TM4SF) family | B cells | Possible role in B cell activation or regulation; calcium ion channel |
| CD21 (CR2; C3d receptor) | 145 kD; regulators of complement activation | Mature B cells, follicular dendritic cells | Receptor for complement fragment C3d; forms a coreceptor complex with CD19 and CD81 that delivers activating signals in B cells; receptor for Epstein-Barr virus |
| CD22 (Siglec-2) | 130–140 kD; Ig superfamily; Siglec family; ITIM in cytoplasmic tail | B cells | Regulation of B cell activation; adhesion molecule |
| CD23 (FcεRIIB) | 45 kD; C-type lectin | Activated B cells, monocytes, macrophages | Low-affinity Fcε receptor, induced by IL-4; function is not clear |
| CD25 (IL-2 receptor α chain) | 55 kD; noncovalently associated with IL-2Rββ (CD122) and IL-2Rγ (CD132) chains to form a high-affinity IL-2 receptor | Activated T and B cells, regulatory T cells (Treg) | Binds IL-2 and promotes responses to low concentrations of IL-2 |
| CD28 | Homodimer of 44-kD chains; Ig superfamily | T cells (all CD4 + and >50% of CD8 + cells in humans; all mature T cells in mice) | T cell receptor for costimulatory molecules CD80 (B7-1) and CD86 (B7-2) |
| CD29 | 130 kD; noncovalently linked to CD49a–d chains to form VLA (β 1 ) integrins | T cells, B cells, monocytes, granulocytes | Leukocyte adhesion to extracellular matrix proteins and endothelium (see CD49) |
| CD30 (TNF receptor superfamily 8 [TNFRSF8]) | 120 kD; TNFR superfamily | Activated T and B cells; NK cells, monocytes, Reed-Sternberg cells in Hodgkin disease | Not established |
| CD31 (platelet/endothelial cell adhesion molecule 1 [PECAM-1]) | 130–140 kD; Ig superfamily | Platelets, monocytes, granulocytes, B cells, endothelial cells | Adhesion molecule involved in leukocyte transmigration through endothelium |
| CD32 (FcγRII) | 40 kD; Ig superfamily; A, B, and C forms are products of different but homologous genes; ITAM in cytoplasmic tail of A form; ITIM in cytoplasmic tail of B form. | B cells, macrophages, dendritic cells, granulocytes | Fc receptor for aggregated IgG; B form acts as inhibitory receptor that blocks activation signals in B cells and other cells |
| CD34 | 105–120 kD; sialomucin | Precursors of hematopoietic cells; endothelial cells in high endothelial venules | ? Role in cell–cell adhesion |
| CD35 (type 1 complement receptor, CR1) | 190–285 kD (four products of polymorphic alleles); regulator of complement activation family | Granulocytes, monocytes, erythrocytes, B cells, follicular dendritic cells, some T cells | Binds C3b and C4b; promotes phagocytosis of C3b- or C4b-coated particles and immune complexes; regulates complement activation |
| CD36 | 85–90 kD | Platelets, monocytes, macrophages, endothelial cells | Scavenger receptor for oxidized low-density lipoprotein; platelet adhesion; phagocytosis of apoptotic cells |
| CD40 | Homodimer of 44- to 48-kD chains; TNFR superfamily | B cells, macrophages, dendritic cells, endothelial cells | Binds CD154 (CD40L); role in T cell-mediated activation of B cells, macrophages, and dendritic cells |
| CD43 | 95–135 kD; sialomucin | Leukocytes (except circulating B cells) | ? Role in cell–cell adhesion |
| CD44 | 80–>100 kD, highly glycosylated | Leukocytes, erythrocytes | Binds hyaluronan; involved in leukocyte adhesion to endothelial cells and extracellular matrix |
| CD45 (Leukocyte common antigen [LCA]) | Multiple isoforms, 180–220 kD (see CD45R); protein tyrosine phosphatase receptor family; fibronectin type III family | Hematopoietic cells | Tyrosine phosphatase that regulates T and B cell activation |
| CD45R | CD45RO:180 kDCD45RA: 220 kDCD45RB: 190-, 205-, and 220-kD isoforms | CD45RO: memory T cells; subset of B cells, monocytes, macrophages CD45RA: naive T cells, B cells, monocytes CD45RB: B cells, subset of T cells | See CD45 |
| CD46 (Membrane cofactor protein [MCP]) | 52–58 kD; regulators of complement activation family | Leukocytes, epithelial cells, fibroblasts | Regulation of complement activation |
| CD47 | 47–52 kD; Ig superfamily | All hematopoietic cells, epithelial cells, endothelial cells, fibroblasts | Leukocyte adhesion, migration, activation; ligand for signal regulatory protein α (SIRPα); “don’t eat me” signal to phagocytes |
| CD49d | 150 kD; noncovalently linked to CD29 to form VLA-4 (α 4 β 1 integrin) | T cells, monocytes, B cells, NK cells, eosinophils, dendritic cells, thymocytes | Leukocyte adhesion to endothelium and extracellular matrix; binds to VCAM-1 and MadCAM-1; binds fibronectin and collagens |
| CD54 (ICAM-1) | 75–114 kD; Ig superfamily | T cells, B cells, monocytes, endothelial cells (cytokine inducible) | Cell-cell adhesion; ligand for CD11aCD18 (LFA-1) and CD11bCD18 (Mac-1); receptor for rhinovirus |
| CD55 (Decay-accelerating factor [DAF]) | 55–70 kD; GPI linked; regulators of complement activation family | Broad | Regulation of complement activation |
| CD58 (Leukocyte function–associated antigen 3 [LFA-3]) | 55–70 kD; GPI-linked or integral membrane protein | Broad | Leukocyte adhesion; binds CD2 |
| CD59 | 18–20 kD; GPI linked | Broad | Binds C9; inhibits formation of complement membrane attack complex |
| CD62E (E-selectin) | 115 kD; selectin family | Endothelial cells | Leukocyte-endothelial adhesion |
| CD62L (L-selectin) | 74–95 kD; selectin family | B cells, T cells, monocytes, granulocytes, some NK cells | Leukocyte-endothelial adhesion; homing of naive T cells to peripheral lymph nodes |
| CD62P (P-selectin) | 140 kD; selectin family | Platelets, endothelial cells (present in granules, translocated to cell surface on activation) | Leukocyte adhesion to endothelium, platelets; binds CD162 (PSGL-1) |
| CD64 (FcγRI) | 72 kD; Ig superfamily; noncovalently associated with the FcR common γ chain | Monocytes, macrophages, activated neutrophils | High-affinity Fcγ receptor; role in phagocytosis, ADCC, macrophage activation |
| CD66e (Carcinoembryonic antigen [CEA]) | 180–220 kD; Ig superfamily; CEA family | Colonic and other epithelial cells | ? Adhesion; clinical marker of carcinoma burden |
| CD69 | 23 kD; C-type lectin | Activated B cells, T cells, NK cells, neutrophils | Binds to and impairs surface expression of S1PR1, thereby promoting retention of recently activated lymphocytes in lymphoid tissues |
| CD74 (Class II MHC invariant chain [I i ]) | 33-, 35-, and 41-kD isoforms | B cells, dendritic cells, monocytes, macrophages; other class II MHC-expressing cells | Binds to and directs intracellular sorting of newly synthesized class II MHC molecules |
| CD79a (Igα) | 33, 45 kD; forms dimer with CD79b; Ig superfamily; ITAM in cytoplasmic tail | Mature B cells | Required for cell surface expression of and signal transduction by the B cell antigen receptor complex |
| CD79b (Igβ) | 37–39 kD; forms dimer with CD79α; Ig superfamily; ITAM in cytoplasmic tail | Mature B cells | Required for cell surface expression of and signal transduction by the B cell antigen receptor complex |
| CD80 (B7-1) | 60 kD; Ig superfamily | Dendritic cells, activated B cells and macrophages | Costimulator for T lymphocyte activation; ligand for CD28 and CD152 (CTLA-4) |
| CD81 (Target for antiproliferative antigen 1 [TAPA-1]) | 26 kD; tetraspan (TM4SF) | T cells, B cells, NK cells, dendritic cells, thymocytes, endothelial cells | B cell activation; forms a coreceptor complex with CD19 and CD21 that delivers signals that synergize with signals from the B cell antigen receptor complex |
| CD86 (B7-2) | 80 kD; Ig superfamily | B cells, monocytes; dendritic cells; some T cells | Costimulator for T lymphocyte activation; ligand for CD28 and CD152 (CTLA-4) |
| CD88 (C5a receptor) | 43 kD; G protein–coupled, seven membrane-spanning receptor family | Granulocytes, monocytes, dendritic cells, mast cells | Receptor for C5a complement fragment; role in complement-induced inflammation |
| CD89 (Fcα receptor [FcαR]Facer) | 55–75 kD; Ig superfamily; noncovalently associated with the common FcR γ chain | Granulocytes, monocytes, macrophages, T cell subset, B cell subset | Binds IgA; mediates IgA-dependent cellular cytotoxicity |
| CD90 (Thy-1) | 25–35 kD; GPI linked; Ig superfamily | Thymocytes, peripheral T cells (mice), CD34 + hematopoietic progenitor cells, neurons | Marker for T cells; unknown function |
| CD94 | 43 kD; C-type lectin; on NK cells, covalently assembles with other C-type lectin molecules (NKG2) | NK cells; subset of CD8 + T cells | CD94/NKG2 complex functions as an NK cell inhibitory receptor; binds human leukocyte antigen E (HLA-E) class I MHC molecules |
| CD95 (Fas) | Homotrimer of 45-kD chains; TNFR superfamily | Broad | Binds Fas ligand; delivers signals leading to apoptotic death |
| CD102 (ICAM-2) | 55–65 kD; Ig superfamily | Endothelial cells, lymphocytes, monocytes, platelets | Ligand for CD11aCD18 (LFA-1); cell–cell adhesion |
| CD103 (α E integrin subunit) | Dimer of 150- and 25-kD subunits; noncovalently linked to β 7 integrin subunit to form α E β 7 integrin | Intraepithelial lymphocytes, other cell types | Role in T cell homing to and retention in mucosa; binds E-cadherin |
| CD106 (VCAM-1) | 100–110 kD; Ig superfamily | Endothelial cells, macrophages, follicular dendritic cells, marrow stromal cells | Adhesion of cells to endothelium; receptor for CD49dCD29 (VLA-4) integrin; role in lymphocyte trafficking, activation |
| CD134 (OX40, TNFRSF4) | 29 kD; TNFR superfamily | Activated T cells | Receptor for T cell CD252; T cell costimulation |
| CD141 (BDCA-3, thrombomodulin) | 60 kD; EGF-like domains | Cross-presenting dendritic cells, monocytes, endothelial cells | Binds thrombin and prevents blood coagulation |
| CD150 (Signaling lymphocyte activation molecule [SLAM]) | 37 kD; Ig superfamily | Thymocytes, activated lymphocytes, dendritic cells, endothelial cells | Regulation of B cell–T cell interactions and lymphocyte activation |
| CD152 (Cytotoxic T lymphocyte–associated protein 4 [CTLA-4]) | 33, 50 kD; Ig superfamily | Activated T lymphocytes, regulatory T cells | Mediates suppressive function of regulatory T cells; inhibits T cell responses; binds CD80 (B7-1) and CD86 (B7-2) on antigen-presenting cells |
| CD154 (CD40 ligand [CD40L]) | Homotrimer of 32- to 39-kD chains; TNFR superfamily | Activated CD4 + T cells | Activation of B cells, macrophages, and endothelial cells; ligand for CD40 |
| CD158 (Killer Ig-like receptor [KIR]) | 50, 58 kD; Ig superfamily; KIR family; ITIMs or ITAMs in cytoplasmic tail | NK cells, T cell subset | Inhibition or activation of NK cells on interaction with appropriate class I HLA molecules |
| CD159a (NKG2A) | 43 kD; C-type lectin; forms heterodimer with CD94 | NK cells, T cell subset | Inhibition or activation of NK cells on interaction with class I HLA molecules |
| CD159c (NKG2C) | 40 kD; C-type lectin; forms heterodimer with CD94 | NK cells | Activation of NK cells on interaction with the appropriate class I HLA molecules |
| CD162 (P-selectin glycoprotein ligand 1 [PSGL-1]) | Homodimer of 120-kD chains; sialomucin | T cells, monocytes, granulocytes, some B cells | Ligand for selectins (CD62P, CD62L); adhesion of leukocytes to endothelium |
| CD178 (Fas ligand [FasL]) | Homotrimer of 31-kD subunits; TNF superfamily | Activated T cells | Ligand for CD95 (Fas); triggers apoptotic death |
| CD206 (Mannose receptor) | 166 kD; C-type lectin | Macrophages | Binds high-mannose-containing glycoproteins on pathogens; mediates macrophage endocytosis of glycoproteins and phagocytosis of bacteria, fungi, and other pathogens |
| CD223 (Lymphocyte-activation gene 3 [LAG3]) | 57.4 kD; Ig superfamily; | T cells, NK cells, B cells, plasmacytoid DCs | Binds class II MHC; inhibits T cell activation |
| CD244 (2B4) | 41 kD; Ig superfamily; CD2/CD48/CD58 family; SLAM family | NK cells, CD8 T cells, γδ T cells | Receptor for CD148; modulates NK cell cytotoxic activity |
| CD247 (TCR ζ chain) | 18 kD; ITAMs in cytoplasmic tail | T cells; NK cells | Signaling chain of TCR complex– and NK cell–activating receptors |
| CD252 (OX40 ligand) | 21 kD; TNF superfamily | Dendritic cells, macrophages, B cells | Ligand for CD134 (OX40, TNFRSF4); costimulates T cells |
| CD267 (TACI) | 31 kD; TNFR superfamily | B cells | Receptor for cytokines BAFF and APRIL; mediates T-independent B cell responses and B cell survival |
| CD268 (BAFF receptor) | 19 kD; TNFR superfamily | B cells | Receptor for BAFF; mediates B cell survival |
| CD269 (B cell maturation antigen [BCMA]) | 20 kD; TNFR superfamily | B cells | Receptor for BAFF and APRIL; mediates plasma cell survival |
| CD273 (PD-L2) | 25 kD; Ig superfamily; structurally homologous to B7 | Dendritic cells, monocytes, macrophages | Ligand for PD-1; inhibits T cell activation |
| CD274 (PD-L1) | 33 kD; Ig superfamily; structurally homologous to B7 | Leukocytes, other cells | Ligand for PD-1; inhibits T cell activation |
| CD275 (ICOS ligand) | 60 kD; Ig superfamily; structurally homologous to B7 | B cells, dendritic cells, monocytes | Binds ICOS (CD278); T cell costimulation |
| CD278 (inducible costimulator [ICOS]) | 55–60 kD; Ig superfamily; structurally homologous to CD28 | Activated T cells | Binds ICOS-L (CD275); T cell costimulation and Tfh differentiation |
| CD279 (PD1) | 55 kD; Ig superfamily; structurally homologous to CD28; ITIM and ITSM in cytoplasmic tail | Activated T and B cells | Binds PD-L1 and PD-L2; inhibits T cell activation |
| CD303 (BDCA2, C-type lectin domain family 4 member C [CLEC4C]) | 25 kD; C-type lectin superfamily | Plasmacytoid dendritic cells | Binds to microbial carbohydrates; inhibits dendritic cell (DC) activation |
| CD304 (BDCA4, Neuropilin) | 103 kD; complement-binding, coagulation factor V/VIII, and meprin domains | Plasmacytoid dendritic cells, many other cell types | Vascular endothelial growth factor A receptor |
| CD314 (NKG2D) | 42 kD; C-type lectin | NK cells, activated CD8 + T cells, NK-T cells, some myeloid cells | Binds MHC class I, and the class I–like molecules MIC-A, MIC-B, Rae1, and ULBP4; role in NK cell and CTL activation |
| CD357 (GITR, TNFRSF18) | 26 kD; TNFR superfamily | CD4 + and CD8 + T cells, Treg | ? Role in T cell/Treg function |
| CD363 (type 1 sphingosine-1-phosphate receptor 1 [S1PR1]) | 42.8 kD; G protein–coupled, seven membrane-spanning receptor family | Lymphocytes, endothelial cells | Binds sphingosine 1-phosphate and mediates chemotaxis of lymphocytes out of lymphoid organs |
| CD365 (hepatitis A virus cellular receptor 1 [HAVCR1], TIM-1) | 38.7 kD; Ig superfamily, T cell transmembrane, immunoglobulin, and mucin family, T cell transmembrane, immunoglobulin, and mucin family | T cells, kidney and testis | Receptor for several viruses |
| CD366 (hepatitis A virus cellular receptor 2 [HAVCR2], TIM-3) | 33.4 kD; Ig superfamily, Ig superfamily, T cell transmembrane, immunoglobulin, and mucin family, T cell transmembrane, immunoglobulin, and mucin family | T cells, macrophages, dendritic cells, NK cells | Receptor for several viruses; binds phosphatidylserine on apoptotic cells; inhibits T cell responses |
| CD369 (CLEC7A, DECTIN 1) | 27.6 kD; C-type lectin | Dendritic cells, monocytes, macrophages, B cells | Pattern recognition receptor specific for fungal and bacterial cell wall glucans |
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