Description: The A4 monoclonal antibody reacts with the class I human leukocyte antigen (HLA) complex in the absence of β2 microglobulin. There are three class I α-chain genes in humans, called HLA-A, -B and -C. Normally, HLA class I proteins are associated non-covalently with β2 microglobulin (β2M). The function of the HLA class I complex is to present peptides derived from intracellular pathogens, including viral pathogens, on the cell surface to antigen specific CD8+ cytotoxic T cells. Class I HLA is expressed by the majority of nucleated cells.
