Maternal T cells of immunized pregnant mice induce immune suppression in their offspring.

The present study focused on the influence of maternal immunity during pregnancy on the responsiveness of the immune system(s) in offspring. Maternal immunization of pregnant mice with T-dependent foreign antigen sheep red blood cells (SRBC) induced suppression of anti-SRBC plaque-forming cell (PFC) responses in their offspring. We attempted to identify the cell species among the maternal lymphoid cells of the immunized pregnant mice that induced this suppression in their offspring, by separating the maternal cells into T cells, B cells and macrophages, or T-cell subsets, and then adoptively transferring them into other normal pregnant mice. The results demonstrated the following: first, maternal CD4+ T cells of immunized pregnant mice induced immune suppression in their offspring. Second, maternal T cells could be activated during pregnancy in the same fashion as in non-pregnant mice. The T-cell factor(s) for the immune suppression in offspring is produced not only by maternal T cells of immunized pregnant mice but also by T cells activated in non-pregnant mice. Third, cellular organization was required for maternal T cells to induce this immune suppression in their offspring.