H-Y antigen and immunity: a means for controlling the secondary sex ratio?

C57BL/6J female mice were splenectomized and then sensitized to the H-Y antigen by means of grafts of H-Y incompatible skin and injections of spleen cells from syngeneic males. When subsequently mated to syngeneic males the secondary sex ratio of progeny born was significantly greater than that of controls. However, the effect was manifest only among the progeny of later litters (i.e., 3, 4, 5) suggesting that repeated exposure to the H-Y antigen during the course of pregnancy was essential to bring about demonstrable immunoregulatory changes.