MHC restriction

antigen recognition by T cells that is restricted to peptide antigens bound to a self-MHC molecule for presentation

Description
MHC restriction refers to stimulation of T cells being restricted to peptide antigens displayed in conjuction with MHC molecules. Therefore, antigen recognition and immune responses are usually restricted to antigens processed for extracellular display bound to MHC molecules. MHC restriction is relevant also during the development and differentiation of primary lymphocytes in thymus and bone marrow, where inappropriate T cells die by apoptosis through positive and negative selection in two developmental stages: upon high affinity for MHC-bound self-antigens and upon insufficient affinity for self-MHC molecules. MHC restriction can be sub-categorised, so that e.g. T helper cells recognize only antigens in conjunction with class II MHC molecules, whereas T cytotoxic cells usually require antigen conjunction with class I MHC molecules.