The Effect of Estrogenic Hormones on Immune Responses in Normal and Irradiated Mice

The effect of estrogenic hormones on survival and immunity was studied in sublethally irradiated, lethally irradiated and syngeneic bone marrow transplanted, and nonirradiated mice. When either estradiol or estriol were administered for 2 weeks after x-irradiation, excessive early mortality occurred. Evaluation of the allograft and hemagglutinin responses in the animals surviving 4 weeks postirradiation revealed that the St. Luke's myeloma, indigenous to the C3H strain, injected into sublethally irradiated AKR mice grew progressively and killed the majority of the estrogen recipients, but regressed in the control-treated irradiated mice; first set allogeneic skin graft survival was prolonged by estradiol in sublethally irradiated mice and by both estrogens in lethally-irradiated recipients; and the primary hemagglutinin response to sheep red cells was markedly depressed by both agents in lethally-irradiated mice and by estradiol in sublethally-irradiated animals. By contrast, neither the survival nor the allograft or hemagglutinin responses were altered by estrogens in nonirradiated normal or pretreated mice. Finally, adoptive immunity was not influenced by hormonal treatment.