REGULATION OF MHC CLASS-I AND CLASS-II GENE-TRANSCRIPTION - DIFFERENCES AND SIMILARITIES

Major histocompatibility complex (MHC) molecules serve as peptide rece ptors. These peptides are derived from processed cellular or extra-cel lular antigens. The MHC gene complex encodes two major classes of mole cules, MHC class I and class II, whose function is to present peptides to CD8(+) (cytotoxic) and CD4(+) (helper) T cells, respectively. The genes encoding both classes of MHC molecules seem to originate from a common ancestral gene. One of the hallmarks of the MHC is its extensiv e polymorphism which displays locus and allele-specific characteristic s among the various MHC class I and class II genes. Because of its cen tral role in immunosurveillance and in various disease states, the MHC is one of the best studied genetic systems. This review addresses sev eral aspects of MHC class I and class II gene regulation in human and in particular, the contribution to the constitutive and cytokine-induc ed expression of MHC class I and II genes of MHC class-specific regula tory elements and regulatory elements which apparently are shared by t he promoters of MHC class I and class II genes.