The major histocompatibility complex (MHC).
D000818:Animals; D006680:HLA Antigens; D000949:Histocompatibility Antigens Class II; D006650:Histocompatibility Testing; D006801:Humans; D008285:Major Histocompatibility Complex
D006680:HLA Antigens; D000949:Histocompatibility Antigens Class II