Expression of Ia and the production of interleukin 1 by peritoneal exudate macrophages activated in vivo by steroids.

The in vivo stimulatory potential of estrogens and progestogens on monocytes/macrophages was examined in peritoneal exudate cells from Balb/cBy mice treated with continuous infusions for 15 days. Mice received a daily dose of 6.6 X 10(-10) M of one of the following compounds: prednisone, testosterone, estrogens--17 beta-estradiol and diethylstilbesterol, progestogens--progesterone and ethisterone and the bile acid lithocholic acid. Although total numbers of peritoneal exudate cells and the percentage of macrophages within those populations did not change with any of the treatments, the number of Ia-positive cells did significantly increase with the two estrogens, the two progestogens and the bile acid given the mice. The production of interleukin 1 was also stimulated by the treatment of the animals with the two estrogens, the two progestogens, and the bile acid, but not the glucocorticoid or testosterone. The activation of Ia expression, therefore, correlated with the production of IL-1. Estrogens and progestogens appear to have a marked effect on in vivo activation of monocytes/macrophages and may relate to differences in females and males in developing immune responses related to the actions of monocytes/macrophages.