Major histocompatibility complex protein (MHC protein) (MHC)

Major histocompatibility complex proteins (MHC proteins) are transmembrane glycoproteins expressed on the surface of cells that present peptide antigens derived from intracellular or extracellular proteins, and are recognized by T cell receptors, thereby initiating and regulating immune responses. Class I MHC proteins present intracellular peptides to CD8+ cytotoxic T cells, while Class II MHC proteins present extracellular peptides to CD4+ helper T cells. MHC proteins are essential for self/non-self recognition and are involved in responses to infectious disease, cancer, autoimmunity, and transplant rejection. The presenting peptide, termed antigen, is typically 8–11 amino acids long for Class I and longer for Class II, and both protein and bound peptide form the ligand recognized by T cells.

Other names

Major histocompatibility complex moleculeMHCHLA (human leukocyte antigen, in humans)MHC class IMHC class II

Competitive blockade of antigen presentation; Modulation of peptide loading and presentation; Alteration of T cell activation/immune modulation