[Effect of interleukin-2 and interleukin-6 on ovary in the ovulatory period--establishment of the new ovarian perfusion system and influence of interleukins on ovulation rate and steroid secretion].

Cytokines are not only mediators of inflammation and the immune system but are also important factors in cell proliferation, differentiation, and cell-to-cell communication. Cytokines have been identified within follicular fluid and some authors indicated that they are playing some roles in ovulation and ovarian steroidogenesis. Interleukin-2 (IL-2), mainly secreted by activated T-cells, influences other T-cells, B-cells, Macrophages, NKcells, etc. and is a major proliferating and differentiation factor of lymphocytes. Interleukin-6 (IL-6) is known to be secreted from and influence immune cells and/or non-immune cells such as fibroblasts, hepatic cells, endothelial cells, etc. The in vitro ovarian perfusion system has some advantages, compared with in vivo study, that is, it is devoid of systemic or unnecessary factors which are not focused on. In this study, the effects of IL-2 and IL-6 on ovulation and steroidogenesis were examined using the newly developed in vitro ovarian perfusion system and the culture of follicular granulosa cells. In the perfusion experiment, 100 ng/ml of IL-6 suppressed LH (100ng/ml)-induced estradiol (E2) secretion but did not influence progesterone (P4) secretion, while IL-2 had no effect on steroid secretion. Both IL-2 (100ng/ml) and IL-6 (100ng/ml) significantly suppressed LH-induced ovulation (ovulation rate; 8.3 +/- 1.5, mean +/- SE), to 2.2 +/- 1.1 and 3.2 +/- 1.0, respectively. Addition of 1.0, 3.0, 10 ng/ml of IL-6 decreased FSH (50ng/ml)-induced E2 secretion dose-dependently in the culture experiments of granulosa cells. IL-6 also suppressed FSH-induced P4 secretion in concentrations of 3.0 and 10 ng/ml. On the other hand, IL-2 concentrations of 10 and 30 ng/ml increased FSH-induced P4 secretion although 100 ng/ml of IL-2 showed no effect. Any dosage of IL-2 did not influence E2 secretion induced by FSH. All of these results obtained in the present study suggest that IL-2 and IL-6 may directly and/or indirectly suppress some mechanisms of ovulation, but with still unclarified different pathways.