The same genetic regions encode minor histocompatibility antigens detectedin the context of different MHC haplotypes

The mammalian genome encodes numerous autosomal minor histocompatibilty (H) antigens that act as a barrier to allogeneic tissue transplantation when d onor and recipient are matched for the major histocompatibilty complex (RHI C). However, most of our understanding of the genetic basis of such minor H antigens is limited to analysis of mouse strains of the H2(b) haplotype. T o broaden our understanding, we investigated minor H antigens detected in t he context of other MHC alleles. As measured by graft survival and precurso r cytotoxic T lymphocytes from blood, our results suggest that chromosomal segments known to encode minor H antigens detected in the context of the H2 (b) haplotype are antigenically complex in that they also frequently encode minor H antigens that can be detected in the context of at least the H2(d) and H2(k) haplotypes. Genetic models to account for this complexity are di scussed.