Suppression of cellular immune reactions by rat ovarian cells

The influence on the immunologic response by rat ovarian cells of follicle and stromal tissue origin was investigated using the mixed lymphocyte reaction (MLR), the phytohemagglutinin (PHA) assay, the cytotoxic T lymphocyte (CTL) assay, and a cytotoxic T-cell-mediated microcytotoxicity test. The MLR between BN/Mai Pfd (RT-In) stimulator splenocytes (mitomycin-C treated) and R/A Pfd (RT-1u) responder lymph node cells was markedly suppressed by ovarian cells of follicle and/or stromal tissue origin. A similar in vitro inhibition was observed with cell-free supernatants from ovarian cells, not only in the rat MLR but also in the mouse MLR between Balb/c stimulator splenocytes and C57B1 responder lymph node cells. Moreover, the reactivity of rat lymphocytes was suppressed when they were cocultured with ovarian cells in the PHA and CTL assays. Preincubation of the supernatants with serial diluted antiprogesterone serum (APS) and antiestradiol serum (AES) revealed that the suppressive effect of these supernatants could be completely abolished with APS--and, to a lesser extent, by AES. As shown by the cell-mediated microcytoxicity assay both the ovarian cells and the steroids secreted by these cells were, however, ineffective in suppressing the effector phase. It is suggested that the steroid secretion by the ovary may play an important role in the prolonged survival of ovarian grafts.