PROBLEM: To study the effects of estradiol (E2) or progesterone on macrophage function in the presence of lipopolysaccharide (LPS).
METHOD OF STUDY: Male rat peritoneal macrophages were treated in vitro with 0.1 μg/mL of LPS and E2 or progesterone.
RESULTS: At 10−2 ng/mL, E2 significantly (P<0.05; n=6) enhanced tumor necrosis factor (TNF) release by LPS-treated macrophages. TNF release was significantly (P<0.05; n=6) inhibited by 102 ng/mL or 103 ng/mL of E2 and by progesterone at less than 10−3 ng/mL or greater than 10−1 ng/mL. E2 (10−4 and 10 ng/mL) and progesterone (10−6–10−4 ng/mL and 102 ng/mL) each significantly (P<0.05, n=8) enhanced H2O2 release by LPS-treated macrophages. E2 (<10−2 and >10 ng/mL) and progesterone (10−7–104 ng/mL) each significantly inhibited (P<0.05; n=6) NO2− release by LPS-treated macrophages.
CONCLUSIONS: Exposure to LPS tended to diminish the effects of E2 and to enhance the effects of progesterone on the parameters determined here. Such LPS-associated alterations in the dose–response profile of macrophages to female sex hormones may contribute to gender-related differences in the immune response under normal and pathological conditions.