[Reproduction and immune factors in women. Pregnancy, habitual abortion and HLA histocompatibility].

Immune tolerance of the mother towards the fetus, which is like an allograft, may be explained partially by the presence of immunosupressor factors produced by the placenta. The maternal production of antibodies against trophoblastic antigens would seem equally necessary to prevent the fetus being rejected by cytotoxic maternal lymphocytes. Where there is marked histocompatibility between partners the protecting antibodies are absent and that gives rise to repeated abortions. This hypothesis is discussed as well as the rationale of treatments that are aimed at increasing maternal production of protective antibodies in cases of habitual abortion.