Androgens inhibit proliferation of human peripheral blood lymphocytes in vitro

The effect of sex hormones on human lymphocytes was examined in vitro on cell cultures of human peripheral blood mononuclear cells (HPBM). Cells were stimulated using T- and B-cell mitogens, and hormones in physiological (nM) or pharmacological (microM) concentrations were added. Proliferation was determined by measuring the incorporation of tritiated thymidine. It was found that both testosterone and dihydrotestosterone, in physiological concentrations, can attenuate DNA synthesis. The effect was dose dependent in that pharmacological concentrations of both testosterone and dihydrotestosterone caused a strong inhibitory effect on proliferation of in vitro cultured HPBM. However, cell cultures of a few individuals were insensitive to the androgens even at pharmacological concentrations. Also, no difference could be detected in the response between cultured cells of females and males. Although a slight reduction in antibody production was evident in pokeweed mitogen-stimulated cultures, in the presence of both testosterone and dihydrotestosterone, it was, however, not statistically significant.