What are the roles of MHC-I and MHC-II?

MHC proteins determine “self” from non-self. Membrane proteins on antigen presenting cells that display peptide antigens for recognition by T lymphocytes. •MHC proteins control immune responses to all peptide antigens recognized by T lymphocytes. •Class I expressed on all nucleated cells; class II on dendritic cells, macrophages, B – lymphocytes.