Estrogens and Chlamydia trachomatis.

Isolates of Chlamydia trachomatis were inoculated in nonreplicating McCoy cells and incubated for 48 hr with various concentrations of hormones. Only the estrogens, particularly 17-beta-estradiol, had an affect on the subsequent infection of the McCoy cells by the Chlamydia. Exposure to 2-4 ng/ml (10(-8) M) estradiol during inoculation and incubation was associated with no change in the initial binding of Chlamydia to McCoy cells, but significantly more (about twofold) Chlamydia inclusions in the McCoy cells after 48 hr incubation. This effect was dose dependent, could be blocked with anti-estrogens, and also occurred with replicating McCoy cells. Localization studies suggest that this effect on the infectivity of Chlamydia trachomatis is dependent upon initial interactions of estrogens with McCoy cells. Both light microscopy and electron microscopy of the McCoy (fibroblast) cells showed no morphological changes after exposure to the estrogens under the incubation conditions employed in these studies. Estrogens may modify host susceptibility to Chlamydia infections in a manner independent of morphological changes in mammalian cells.