Cluster of Differentiation (CD Markers)
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The cluster of differentiation (CD) is a protocol used for the identification and investigation of cell surface molecules present on leukocytes. CD molecules can act in numerous ways, often acting as receptors or ligands (the molecule that activates a receptor) important to the cell. A signal cascade is usually initiated, altering the behavior of the cell (see cell signaling). Some CD proteins do not play a role in cell signaling, but have other functions, such as cell adhesion. There are approximately 250 different proteins.
The CD nomenclature was proposed and established in the 1st International Workshop and Conference on Human Leukocyte Differentiation Antigens (HLDA). This system was intended for the classification of the many monoclonal antibodies (mAbs) generated by different laboratories around the world against epitopes on the surface molecules of leukocytes (white blood cells). Since then, its use has expanded to many other cell types, and more than 320 CD unique clusters and subclusters have been identified. The proposed surface molecule is assigned a CD number once two specific monoclonal antibodies (mAb) are shown to bind to the molecule. If the molecule has not been well-characterized, or has only one mAb, it is usually given the provisional indicator "w" (as in "CDw186").
The CD system is commonly used as cell markers; this allows cells to be defined based on what molecules are present on their surface. These markers are often used to associate cells with certain immune functions or properties. While using one CD molecule to define populations is uncommon (though a few examples exist), combining markers has allowed for cell types with very specific definitions within the immune system.
Reactivity of the most common antibodies (CD Markers) used in Flow Cytometric Evaluation of Hematolymphoid Neoplasms:
| Antibody (CD) | Reactivity |
| CD1a | Thymocytes and immature T cells |
| CD2 | T cells, Large granular lymphocytes (LGL), NK cells, some APL, neoplastic mast cells |
| CD3 | T cells, primary effusion lymphoma |
| CD4 | T cells (helper/inducer), monocytes, myeloblasts, NK cell lymphoma |
| CD5 | T cells, B-CLL/SLL, MCL |
| CD7 | T cells, some myeloblasts |
| CD8 | T cells (suppressor/cytotoxic), large granular lymphocytes (LGL) |
| CD10 | Follicle center cells, FL, some DLBCL, pre-B-ALL, pre-T-ALL, thymocytes, BL |
| CD11b | Granulocytes, monocytes |
| CD11c | Monocytes, HCL, LGL, activated T cells, MZL |
| CD13 | Myeloid cells, rare pre-B-ALL |
| CD14 | Monocytes |
| CD15 | Granulocytes, Hodgkin's lymphoma |
| CD16 | Granulocytes, NK cells, LGL |
| CD19 | B cells, pre B-ALL, subset of AML (AML1/ETO with t(8;21)) |
| CD20 | B cells, rare plasma cell myelomas |
| CD22 | B cells |
| CD23 | B-CLL/SLL, plasma cells, follicular dendridic cells |
| CD25 | HCL, subset of B and T cell lymphomas |
| CD30 | Hodgkin's lymphoma, anaplastic large cell lymphoma, subset of DLBCL, subset of B cell lymphoma |
| CD33 | Myeloid cells, rare pre B-ALL, rare blastic NK lymphoma |
| CD34 | myeloblasts, lymphoblasts, endothelial cells |
| CD38 | Plasma cells, activated T and B cells, subset B-CLL/SLL, epithelial cells |
| CD41 | Megakaryocytes |
| CD43 | Myeloid cells, T-cell lymphoma, pre B ALL, pre T ALL, B cell lymphoma (subset), plasma cells |
| CD56 | NK cells, LGL |
| CD57 | NK cells, LGL |
| CD61 | Megakaryocytes |
| CD79a | B cells, plasma cells, megakaryocytes |
| CD103 | HCL, rare T cell lymphomas |
| CD117 | AML, mast cells, stromal tumors (GIST), plasma cells |
| bcl-2 | Mature B cells, (except benign GCC), T cells, and FL |
| Heavy Chains (IgG, IgA, IgM, IgD) | B cells, plasma cells, DLBCL with ALK expression |
| HLA Dr | AML (except APL), B cells monocytes |
| Light chains (kappa or lambda) | B cells (surface), plasma cells (cytoplasmic) |
| TdT | pre-B-ALL, pre-T-ALL, some AML and hematogones |
For a complete list and description of the most current Cluster of Differentiation:
http://www.hcdm.org/MoleculeInformation/tabid/54/Default.aspx
http://en.wikipedia.org/wiki/List_of_human_clusters_of_differentiation
References: