CD4: a co-receptor in the immune response and HIV infection.
CD4 is a transmembrane glycoprotein of the immunoglobulin superfamily, expressed on developing thymocytes, major histocompatibility class II (class II MHC) restricted mature T lymphocytes and, in humans, on cells of the macrophage/monocyte lineage. On lymphoid cells, CD4 plays a critical role during thymocyte ontogeny and in the function of mature T cells. CD4 binds to non-polymorphic regions of class II MHC acting as a co-receptor for the T-cell antigen receptor (TCR). It increases avidity between thymocytes and antigen-presenting cells and contributes directly to signal transduction through association with the Src-like protein tyrosine kinase p56lck. Its precise role on monocytes and macrophages is unclear. CD4 is also a co-receptor for the human and simian immunodeficiency viruses (HIV-1, HIV-2 and SIV). Clinically, CD4 antibodies may be used to achieve immunological tolerance to grafts and transplants.
Bowers
K
K
Medical Research Council Laboratory for Molecular Cell Biology, University College London, U.K.
Pitcher
C
C
Marsh
M
M
D000818:Animals; D000911:Antibodies, Monoclonal / Q000627:therapeutic use; D000917:Antibody Formation; D015704:CD4 Antigens / Q000737:chemistry / Q000276:immunology*; D015488:HIV Antigens / Q000737:chemistry / Q000276:immunology*; D015658:HIV Infections / Q000276:immunology* / Q000628:therapy; D006801:Humans; D051379:Mice; D010452:Peptide Biosynthesis; D017434:Protein Structure, Tertiary; D051381:Rats; D013329:Structure-Activity Relationship
D000911:Antibodies, Monoclonal; D015704:CD4 Antigens; D015488:HIV Antigens