Potential Roles of a Special CD8αα+ Cell Population and CC Chemokine Thymus-Expressed Chemokine in Ovulation Related Inflammation

Abstract

It is well known that ovulation may be an inflammatory process. However, it remains elusive how immune cells participate in this process. We have identified a novel CD8alpha alpha(+) population, which resembles tissue dendritic cells, in the theca of antral follicles. We further observed a dramatic influx of the CD8alpha alpha(+) cells into the ovulating follicles. This CD8alpha alpha(+) population was absent in the ovary of estradiol-induced anovulatory C31F(1) mice and subfertile athymic nude mice. Expression of a CC chemokine thymus-expressed chemokine (TECK) has previously been found in the ovary; we further demonstrated that TECK attracted CD8alpha alpha(+) cells into the ovary. Anti-TECK Ab, elicited in the female mice by active immunization, depleted the ovarian CD8alpha alpha(+) cells in vivo. Mice with a high titer of TECK Ab failed to ovulate after superovulation induction. More importantly, the immunized mice had greatly reduced fertility, which was positively correlated with the Ab titers. Ovarian TECK expression was normal in anovulatory C31F(1) mice, suggesting that infertility in the immunized mice is due to a block of CD8alpha alpha(+) cell migration. Finally, the origin of ovarian CD8alpha alpha(+) cells was explored. Upon being transferred, thymic CD8alpha(+) cells were able to home to the theca of follicles in the recipients. Thus, ovarian CD8alpha alpha(+) cells, which participate in the ovulation-related inflammation, may originate in the thymus.