Influence of estrogen on host resistance: increased susceptibility of mice to Listeria monocytogenes correlates with depressed production of interleukin 2.

Mice given pharmacological levels of the synthetic estrogen diethylstilbestrol demonstrated a marked increase in susceptibility to infection with Listeria monocytogenes. Experiments were performed in an effort to determine the mechanism(s) by which estrogen treatment increases the susceptibility of mice to L. monocytogenes infection. Estrogen exposure depressed the in vivo proliferative response of splenic lymphocytes to L. monocytogenes, which correlated with the decreased in vitro response of these cells to phytohemagglutinin. Interleukin 2 (IL 2) production by splenic lymphocytes from estrogen-treated mice was decreased, although these cells were capable of proliferating normally in response to exogenous IL 2. Interleukin 1 production by peritoneal macrophages was not depressed by estrogen exposure. The number of bacteria observed in the spleens of estrogen-exposed mice challenged with L. monocytogenes was reduced by IL 2 administration. Thus, estrogens may decrease host resistance to L. monocytogenes by inhibiting IL 2 production and the subsequent proliferation of antigen-sensitized T lymphocytes required for recovery.