Several Hundred Allelic Variants Have Been Identified In Humans However, up to 6 MHC I And 12 MHC II Molecules Are Expressed In An Individual Enormous Number Of Peptides Needs To Be Presented Using These MHC Molecules To Achieve This Task MHC Molecules Are Not Very Specific For Peptides (Unlike TCR and BCR) Promiscuous Binding Occurs --A peptide can bind a number of MHC --An MHC molecule can bind numerous peptides Class I And II Specificity