[Immune reaction between maternal and fetal tissue at the nidatory site of tubal pregnancy].

From the standpoint of local immunity of the nidatory site, the morphological appearance of 85 cases of tubal pregnancies whose nidatory sites were histologically proven, was analyzed. Also, the localization of human chorionic gonadotropin or hCG, a locally strong immunosuppressive substance, was immunohistochemically observed at the nidatory site in five cases of tubal pregnancies, aiming at the clarification of the feto-maternal immune reaction in early human pregnancy. In 48 cases out of 85 (56%), the basic structure of the nidatory site was observed, while in 37 out of 85 (46%), it was not. This shows that in some cases of tubal pregnancy, fibrinoid layer or lymphocytic layer was not always well developed. The finding that a band of lymphocytes appeared around the nidatory site seemed to show the existence of antigenicity of trophoblasts and of feto-maternal immune reaction at the implanted site. However, it was considered that there was little possibility of the lymphocytes participating in the rejection of the fetal tissues. Though the direct immunosuppressiveness of purified hCG is in dispute, the characteristic localization of hCG at the nidatory site suggested a possible role of the trophoblast in the trophoblastic shell with a great amount of hCG on local immunosuppressiveness at the nidatory site.