Monoclonal antibodies against maternal major histocompatibility complex class I molecules induce rapid abortion in mice

PROBLEM: The role of antibodies against fetal or maternal antigens in maint aining or losing pregnancy is not clear. METHOD OF STUDY: Term-pregnant mice were injected with monoclonal antibodie s against only fetal or fetal and maternal major histocompatibility complex class I molecules. The development of pregnancy was then followed. RESULTS: Antibodies against maternal, but not fetal, major histocompatibili ty complex class I molecules induced abortion in mice. The abortion occurre d 6-8 hr after the administration of autoreactive antibodies. The abortion could only be induced after the formation of placenta. antibodies against t umor necrosis factor-alpha could not prevent or postpone the abortion. Exte nsive bleeding has been detected in the placenta of aborting mice 3 hr afte r the administration of the antibodies. CONCLUSIONS: This study indicates that autoreactive antibodies present risk for pregnancy and that the damage leading to abortion induced by such anti bodies most likely occurs at the maternal side of placenta.