CD4, clone SK3, is derived from hybridization of mouse NS-1 myeloma cells with spleen cells from BALB/c mice immunized with human peripheral blood T lymphocytes.
CD69, clone L78, is derived from hybridization of mouse Sp2/0-Ag14 myeloma cells with lymph node cells from BALB/c mice immunized with a CD8+ alloantigen-directed cytotoxic T-lymphocyte (CTL) cell line.
CD3, clone SK7, is derived from hybridization of mouse NS-1 myeloma cells with spleen cells from BALB/c mice immunized with human thymocytes.
CD4 recognizes an antigen that interacts with class II molecules of the major histocompatibility complex (MHC). CD4 is the primary receptor for the human immunodeficiency virus (HIV). The cytoplasmic portion of the antigen is associated with the protein tyrosine kinase p56lck. The CD4 antigen may regulate the function of theCD3 antigen/T-cell antigen receptor (TCR) complex. CD4 also reacts with monocytes/macrophages that have an antigen density lower than that on helper/inducer T lymphocytes. CD69 recognizes a very early human lymphocyte activation antigen.
The CD69 antigen is a surface homodimer formed by the association of 28-kilodalton (kd) and 32-kd chains that are held together by disulfide bridges.
CD3 recognizes the epsilon chain of the CD3 antigen/T-cell antigen receptor (TCR) complex. This complex is composed of at least six proteins that range in molecular weight from 20 to 30 kd. The antigen recognized by the CD3 antibody is noncovalently associated with either α/β or γ/δ TCR (70 to 90 kd).