[Immunological and cytogenetic studies on early spontaneous abortions].

To reveal the role of maternal immunological mechanisms in early spontaneous abortions, the blocking effect (BE) of the maternal serum was evaluated in a mixed lymphocyte culture, and the chromosome constitution of the abortuses was examined. 1) The mean BE in non-pregnant women as a control (n = 7) was 0.86%. 2) The mean BE in women with an uneventful course of pregnancy (n = 21) was 24.1%, which was significantly higher than that in the non-pregnant women (p < 0.01). 3) Seventeen of the 36 abortuses (47.2%) were chromosomally abnormal. 4) The mean BE among all the patients with spontaneous abortions (n = 36) was -9.8%, which was significantly lower than that in the pregnant women (p < 0.01). However, no difference in mean BE was observed between the patients with chromosomally normal (-8.4%) and abnormal abortuses (-11.2%). 5) In addition, no difference in mean BE was observed between the patients with an abortus with a positive fetal heart beat and the patients with an abortus with a negative fetal heart beat. These results indicate that the decreased BE observed in patients with early spontaneous abortion is a consequence of abortion rather than the cause of abortion.