Regulation of immune response by MHC-linked genes

In conclusion, we know that the K region is involved in several H-2 restrictions, the I region in several immune responses, and the D region in immune regulation. The basic function of these gene products is probably immune surveillance by antigen presentation. The main difference is what antigens do they present? Each molecule has the capability to present certain classes of antigens. Whether this selectivity is based on actual primary sequence of these molecules in relation to the antigens is still an open question. Since most normal populations are heterozygous, the number of gene products that can be involved in such surveillance is doubled. We know that complementation between different genes within the MHC complex produces unique products, and complementation also occurs between genes on different chromosomes in heterozygotes to produce hybrid products. Further, non-H-2 genes could also be involved in immune surveillance. This diversity within an individual and the polymorphism within the species are essential for optimum fitness and survival.