TABLE Most Common CD Markers Used in Clinical Practice 14.1 Marker Main Cellular Expression Function/Identity Molecular Weight (kDa) CD1 T cells in the midstage of development Interact with MHC I molecules Developmental markers for T cells and Langerhans’ cells of the skin 49 CD2 T cells Adhesion molecules Used as clinical markers for T cells 50 CD3 T cells Form complex with T-cell receptor (TCR) 100 CD4 Helper T cells, monocytes, macrophages Members of immunoglobulin superfamily Interact with MHC II molecules Bind viral protein gp120 of HIV-1 and HIV-2 56 CD5 T cells, some B cells Costimulatory molecules High levels in chronic lymphocytic leukemia 67 CD7 T cells Members of immunoglobulin superfamily Bind the PI-3 kinase Useful clinical markers for T-cell leukemia stem cells 40 CD8 Cytotoxic T cells Members of immunoglobulin superfamily Interact with MHC I molecules 34 CD9 B cells, T cells, monocytes, eosinophils, basophils, platelets, endothelial cells Facilitate aggregation of platelets, cell adhesion, and cell migration 24 CD10 Pre-B cells, pre-T cells Zinc metalloproteas Common markers for acute lymphoblastic leukemia 100 CD16a NK cells, granulocytes,  monocytes Clinical markers for NK cells Function as Fc receptors for aggregated IgG Mediate phagocytosis and antibody-dependent cell-mediated cytotoxicity 27 CD19 B cells, dendritic cells Coreceptors with CD21 Clinical markers for all stages of B-cell development 90 continued next page chapter 14 Lymphatic System CE LLS OF TH E LYM PHATIC SYSTE M CD20 B cells Form Ca2channels Markers for late stage of B-cell development 37 CD21 B cells, follicular dendritic cells Receptors for C3d complement protein and for Epstein-Barr virus 145 CD22 B cells B-lymphocyte cell adhesion molecules Mediate B-cell to T-cell adhesion 140 CD24 B cells, granulocytes, epithelial cells Expressed in late stage of B-cell differentiation 41 CD28 T cells T-cell costimulatory molecule interacts with CD80 (B7.1) and CD86 (B7.2); the costimulatory signal induces T-cell activation and IL-2 production 44 CD34 Hemopoietic stem cells (HSCs) Clinical markers for HSCs and ligand for CD62L Mediate attachment of stem cells to bone marrow extracellular matrix 120 CD35 T cells, B cells, monocytes, dendritic cells, granulocytes, erythrocytes Complement receptor 1 Promote phagocytosis of complement-coated particles Bind C3b and C4b complement protein 250 CD38 Activated T cells NAD glycohydrolase Used as markers for T-cell activation and proliferation 45 CD40 B cells, macrophages, dendritic cells Active in proliferating B cells Costimulatory molecules for CD40L (CD154) Facilitate cytokine production in macrophages and dendritic cells 48 CD40L Activated CD4T cells; known as CD154 Facilitate interaction between T and B cells Regulate B-cell function Costimulatory molecules for CD40 39 CD45 All human leukocytes Thyrosine phosphatase Leukocyte common antigen 220 CD56 NK cells Clinical markers for NK cells Isoforms of neural adhesion molecules (N-CAM) 135 CD62L Leukocytes Bind CD34 Represent L-selectins, leukocyte adhesion molecules that allow lymphocytes to roll along the endothelial surface 150 CD80 B cells, macrophages, dendritic cells, monocytes, macrophages APC costimulatory molecule interacts with CD28 45 CD86 Activated B cells, macrophages, monocytes, dendritic cells,  endothelial cells APC costimulatory molecule interacts with CD28 70 CD94 NK cells Clinical markers for NK cells 43 TABLE Most Common CD Markers Used in Clinical Practice (Cont.)14.1 Marker Main Cellular Expression Function/Identity Molecular Weight (kDa) APC, antigen-presenting cell; NK, natural killer.