CD3 complex is crucial in transducing antigen-recognition signals into the cytoplasm of T cells and in regulating the cell surface expression of the TCR complex. T cell activation through the antigen receptor (TCR) involves the cytoplasmic tails of the CD3 subunits CD3 gamma, CD3 delta, CD3 epsilon and CD3 zeta. These CD3 subunits are structurally related members of the immunoglobulins super family encoded by closely linked genes on human chromosome 11. The CD3 components have long cytoplasmic tails that associate with cytoplasmic signal transduction molecules. This association is mediated at least in part by a double tyrosine-based motif present in a single copy in the CD3 subunits. CD3 may play a role in TCR-induced growth arrest, cell survival and proliferation. The CD3 antigen is present on 68-82% of normal peripheral blood lymphocytes, 65-85% of thymocytes and Purkinje cells in the cerebellum. It is never expressed on B or NK cells. Decreased percentages of T lymphocytes may be observed in some autoimmune diseases. CD19 is a member of the immunoglobulin superfamily and has two Ig like domains. The CD19 molecule is expressed on 100% of the peripheral B cells as defined by expression of kappa or lamda light chains. It appears to be expressed on myeloid leukemia cells, particularly those of monocytic lineage. Leukemia phenotype studies have demonstrated that the earliest and broadest B cell restricted antigen is the CD19 antigen. The receptor for CD19 is an important functional regulator of normal and malignant B cell proliferation. It is expressed in all B cell precursor leukemias.
B-lymphocyte antigen CD19; B-lymphocyte surface antigen B4; CD19; CD247; CD247 antigen, zeta subunit; CD3 antigen, delta subunit; CD3 delta; CD3 epsilon; CD3-epsilon; CD3d; CD3d antigen, delta polypeptide (TiT3 complex); CD3d molecule, delta (CD3-TCR complex); CD3e; CD3e antigen, epsilon polypeptide (TiT3 complex); CD3e molecule, epsilon (CD3-TCR complex); CD3g; CD3g antigen, gamma polypeptide (TiT3 complex); CD3g molecule, epsilon (CD3-TCR complex); CD3g molecule, gamma (CD3-TCR complex); CD3Z antigen, zeta polypeptide (TiT3 complex); CD3zeta chain; Differentiation antigen CD19; FLJ18683; OKT3, delta chain; T-cell antigen receptor complex, epsilon subunit of T3; T-cell antigen receptor complex, gamma subunit of T3; T-cell antigen receptor complex, zeta subunit of CD3; T-cell receptor T3 delta chain; T-cell receptor T3 gamma chain; T-cell receptor T3 zeta chain; T-cell surface antigen Leu-12; T-cell surface antigen T3/Leu-4 epsilon chain; T-cell surface glycoprotein CD3 delta chain; T-cell surface glycoprotein CD3 epsilon chain; T-cell surface glycoprotein CD3 gamma chain; T-cell surface glycoprotein CD3 zeta chain; TCR zeta chain