Specific immune tolerance during pregnancy after renal transplantation

Pregnancy is associated with specific immunological tolerance to fetal antigens suggesting that immunoregulatory processes during pregnancy can induce specific immunological unresponsiveness. We report a case of a female renal transplant recipient who stopped immunosuppressive therapy during first pregnancy. Despite histologically proven acute renal allograft rejection during the early course of transplantation, no immunological response was observed for 9 years after withdrawal of immunosuppression. Two further pregnancies within that time period did not evoke any renal complications, but were complicated by premature rupture of the amnion and by the development of preeclampsia. To our knowledge, there are no reports of such a long-term specific unresponsiveness to a renal allograft without immunosuppressive therapy. Natural and active immunoregulatory mechanism can be related for the development of specific immune tolerance to renal allograft in this case.