Cell Surface Markers of T-cells, B-cells and Macrophages

An understanding of the distinct families of molecules present on different cells of the immune system provides the tools for distinguishing these cell types in both diagnosis and therapy, as well as understanding the molecular basis for many lymphoid cell functions. Diagnostic MARKERS for T-cells include the T-cell receptor (TcR) with its associated CD3 signaling complex as well as CD5 and the E-receptor (CD2). The presence of membrane immunoglobulin (mIg), which functions as antigen receptor, is diagnostic for B-cells. Complement receptors (CR) and Fc receptors (FcR) which can mediate opsonization, and MHC Class II molecules which are important in antigen presentation, are present on B-cells and macrophages (as well as dendritic cells). Two major classes of T-cells are distinguished by the presence of either CD4 (on TH and Treg) or CD8 (on TCcell). TH cells can be further subdivided into TH1,TH2 and TH17, which produce different combinations of cytokines and have distinct physiological roles.