Inhibition of human endometrial stromal cell proliferation by interleukin 6

We investigated the ability of interleukin 6 (IL-6) to modulate human endometrial stromal cell growth in vitro. Stromal cell proliferation in response to treatment with varying concentrations of IL-6 was determined. Endometrial tissue was obtained from 10 normally cycling women during the secretory phase of their menstrual cycle. Treatment with IL-6 resulted in a dose- and cell-density-dependent inhibition of endometrial stromal cell proliferation in vitro. The maximal inhibition was observed with 200 pg/ml of IL-6 and at a concentration of 10(5) cells/well. During in-vitro culture, stromal cells produced low amounts of IL-6 and demonstrated the presence of IL-6 receptor. These data demonstrate that IL-6 acts as a growth-regulatory signal for human endometrial stromal cells. We postulate that IL-6 may contribute to the maintenance of homeostasis in normal endometrium and that perturbation of IL-6 mediated responses may play a role in disorders of the endometrium such as endometrial cancer and endometriosis.