Altered mitogen- and alloantigen-induced lymphoproliferative responses in primary lymphoid organs of pregnant mice.

The effect of syngeneic murine pregnancy on the response of lymphocytes from the primary lymphoid organs to mitogenic and alloantigenic stimulation was investigated. Thymocytes and bone marrow cells from gravid animals were found to exhibit elevated reactivity to T cell mitogens and allogeneic stimulator cells. In contrast, the LPS response of bone marrow cells from pregnant mice did not differ significantly from that of virgin animals. These findings indicate that the immune reactivity of T cells derived from the primary lymphoid organs is altered during syngeneic murine pregnancy. Pregnancy-induced modifications in T lymphocyte reactivity may contribute to the ability of the maternal immune system to recognize and react against fetal antigens.