Regulatory T cells in pregnancy. VI. Evidence for T-cell-mediated suppression of CTL generation toward paternal alloantigens

The reactivity of spleen cells from allogeneically pregnant mice was assayed versus paternal strain target cells by a direct ⁵¹Cr-release assay. Despite multiple allogeneic parities, the lytic indexes of spleen cells were equivalent to those observed with nonpregnant controls. In view of previously obtained in vivo and in vitro results, spleen cells of allogeneically pregnant mice were added at the onset of MLC-CMLs³ of maternal strain responder cells versus paternal strain stimulator and target cells and studied for regulatory capacities. They did exert a suppressive effect, assessed by ⁵¹Cr release per culture. For the most, this effect was on the CTL induction, not the effector phase. The suppression of CTL generation was specific and mediated by a Thy 1⁺, Ly 2⁺ cell.