<Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (October 2015) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (October 2015) (Learn how and when to remove this template message) </Td> </Tr> <P> The major histocompatibility complex (MHC) is a set of cell surface proteins essential for the acquired immune system to recognize foreign molecules in vertebrates, which in turn determines histocompatibility . The main function of MHC molecules is to bind to antigens derived from pathogens and display them on the cell surface for recognition by the appropriate T - cells . MHC molecules mediate interactions of leukocytes, also called white blood cells (WBCs), which are immune cells, with other leukocytes or with body cells . The MHC determines compatibility of donors for organ transplant, as well as one's susceptibility to an autoimmune disease via crossreacting immunization . The human MHC is also called the HLA (human leukocyte antigen) complex (often just the HLA). The mouse MHC is called the H - 2 complex or H - 2 . </P> <P> In a cell, protein molecules of the host's own phenotype or of other biologic entities are continually synthesized and degraded . Each MHC molecule on the cell surface displays a molecular fraction of a protein, called an epitope . The presented antigen can be either self or non-self, thus preventing an organism's immune system targeting its own cells . In its entirety, the MHC population is like a meter indicating the balance of proteins within the cell . </P>

What is the function of the major histocompatibility complex