The major histocompatibility complex (MHC) is a large family of cell surface molecules in all vertebrates which controls a major part of the immune system. The MHC family can be divided into three groups: Class I, which present intracellular antigens to CD8 T cells; Class II, which present extracellular antigens to CD4 cells; and Class III, which includes several secreted proteins with immune functions such as components of the complement system, cytokines and heat shock proteins. MHC molecules are incredibly important to ensure that the appropriate type of T cell is activated in response to invasion by a foreign pathogen.


MHC Class II (OX-6)

MHC Class I