Maternal-fetal disparity at multiple minor histocompatibility loci affects the weight of the feto-placental unit in mice.

Inbred mice from selected unrelated and congenic strains were mated to determine the relative effects of maternal-fetal disparity at major histocompatibility complex (H-2) and non-H-2 minor histocompatibility antigens on the feto-placental unit at 14 days of gestation. A significant increase in weight of the feto-placental unit was observed only when mother and fetus differed at multiple minor histocompatibility loci. No increase in the weight of the feto-placental unit was observed when mother and fetus differed only at H-2. These results suggest that immunostimulation of the fetus results from a maternal response to minor histocompatibility antigens and not to H-2 antigens.