Sex-associated differences in the regulation of immune responses controlled by the MHC of the mouse.

The immunologic potential of T lymphocytes and antigen-presenting cells (APC) from male and female mice were compared. Lymphocytes from female mice or from male mice that cannot produce and respond to testosterone (Tfm/y) were more reactive than male lymphocytes to alloantigens in MLR. Spleen cells from Tfm/y mice equipped with estrogen implants showed a higher responsiveness than control Tfm/y to alloantigens. The removal of suppressive adherent cells or the addition of T cell growth factor (TCGF) enhanced the proliferative activity of the cells in the MLR. The responsiveness of female cells to alloantigens, however, remained superior to that observed in male cells. Similarly, in the presence of TCGF, thymocytes from female mice react more effectively than male cells in MLR. In addition, Con A-stimulated spleen cells from female mice produce more interleukin 2 (IL 2) than do spleen cells from males or female mice treated with testosterone. Lymphocytes from immunized mice were tested for their ability to respond to soluble antigens (KLH and OVA) in vitro. Again, female immunocompetent cells respond more vigorously than male cells or cells originating in female mice with testosterone implants. APC from female spleen were more efficient than male APC in initiating a secondary response in primed lymphocytes from either males or female mice. Moreover, castration of male mice enhanced, and treatment of female mice with androgen reduced, the efficiency of antigen presentation. In conclusion, these data suggest that female cells are superior to male cells in immunologic functions that are known to be associated with reactions to and recognition of histocompatibility antigens, i.e., antigen presentation and MLR. Furthermore, our present data indicate that the differential reactivity of immunocytes between male and female mice depends on the hormonal balance of the animal.