CD3 consists of five different polypeptide chains (designated as gamma, delta, epsilon, zeta, and eta). The CD3 complex is closely associated at the lymphocyte cell surface with the T cell antigen receptor (TCR). It is involved in signal transduction to the T cell interior following antigen recognition, which culminates in cytokine release, cellular proliferation. CD3 antigen is a highly specific marker for T cells, and is present in majority of T cell neoplasms.Synonyms: CD3 zeta chain, T-cell receptor T3 zeta chain, T-cell surface glycoprotein CD3 zeta chain, T3Z, TCRZ