Cluster of Differentiation /CD antigens, are cell surface antigens of leukocytes, and important for immune reactions of organisms. CD antigens found in various immune cell populations like B cells, T cells, Dendritic cells and NK cells. As lymphocytes mature, they express different protein receptors on the cell surface, which can aid in determining the type and maturation stage of the cells being examined. These proteins or antigen markers are called Clusters of Differentiation.
CD antigens serve as receptors and ligands, and regulate cell signalling and adaptive immunity. CD antigens are commonly used for immunology, cancer and stem cell biology research, such as immunotherapy, tumor-associated and drug target.