Biochemical characterization of Ia antigens encoded by the RT1.B and RT1.D loci in the rat MHC

Ia antigens in rats are genetically associated with typical MHC-linked immune response (Ir) genes. One rat Ir gene (IR-GLT) has recently been mapped to the RT1.D locus in a rat MHC recombinant, WRC. We have studied the expression of Ia antigenic determinants in WRC and its parental strains BN and WRA using a panel of monoclonal antibodies. Our results suggest that the inheritance of IR-GLT corresponds with the inheritance of I-E-like, but not I-A-like, antigens in the WRC rat. These observations were confirmed when WRC I-E-like antigens were analyzed by two-dimensional gel electrophoresis. We propose that RT1.D shares both functional and antigenic homologies with the mouse I-E subregion.