Complex Regulation of MHC Class I Expression: Constitutive and Modulated Patterns of Expression

The major transplantation antigens encoded by class I genes of the major histocompatibility complex (MHC) play a key role in a number of immunological processes, particularly in the recognition of foreign antigens by cytotoxic T cells of the host (Zinkernagel and Doherty 1980). The MHC class I heavy chain (37–45 kd) are non covalently associated on the cell surface with the non-polymorphic beta-2-microglobulin (beta-2m) light chain (12 kd).