HLA Class I
The major histocompatibility complex (MHC) is a system of genes encoding molecules expressed on the cell surface that are required for antigen presentation to the immune system. In humans, this system is called human leukocyte antigen or HLA genes, since it was discovered through antigenic differences among white blood cells from different individuals in the search for polymorphic antigens to match for transplantation. HLA class I molecules are of key importance in the cell-mediated antitumor immune response against viral infections and transformed cells by presenting peptide antigens to cytotoxic T lymphocytes.
The classical HLA class I and class II molecules (HLA-ABC and HLA-DR, HLA-DP, HLA-DQ, respectively) are cell-surface glycoproteins closely related in structure and function. HLA class I molecules consist of two polypeptide chains, a heavy chain of 340 amino acids encoded in chromosome 6 and a light non-polymorphic chain, β2-microglobulin (β2-m),...