Reactivity of xenogeneic antihuman Ia antisera with the I-C subregion of the murine major histocompatibility complex. I. Genetic studies.

Several rabbit xenoantisera raised against human serum Ia antigens have been shown to detect murine lymphocyte antigens. The murine system detected was shown to be polymorphic and expressed on B cells and not T cells. Serological analysis of recombinant H-2 strains demonstrated that two of the antisera recognized products of the I-Cd subregion, and one antiserum recognized products of the I-Cb subregion, thus clearly establishing the existence of the I-C subregion in these two haplotypes. However, as the I-Cd subregion is classically described by the Ia.6 specificity present on T cells and xenoantisera detect a product on B cells, the indication is that the I-C region, like I-A and I-J, complex and contains genes coding for specificities on T cells or B cells.