Nonhuman Primate Mhc-DP Genes

The primate MHC class II region consists of six gene families, DP, DN, DM, DO, DQ, and DR, arranged respectively from centromere to telomere (Trowsdale et al. 1991). The DM, DP, DQ, and DR families each contain genes coding for the α- and β-chains of the class II molecules (the A and B genes, respectively), whereas in DN only one A gene and in DO only one B gene have thus far been identified. The MHC class II genes code for cell surface glycoprotein receptors which bind peptides derived from processed antigens and present them to helper T cells (Klein 1986; Bjorkman et al. 1990; Brown et al. 1993). The class II molecules exhibit differential tissue distribution; their constitutive expression is restricted primarily to cells of the immune system such as B cells, activated T lymphocytes, macrophages, and dendritic cells (Klein 1986).