[Studies of humoral immunological response on the aborted trophoblasts (author's transl)]

To elucidate whether a humoral immune mechanism does involve in genesis of spontaneous abortion (SpA), comparative study on dynamics of immunoglobulin (Ig) and complement (C) was performed between SpA and normal pregnancy in the first trimester (NP-I). IgG, IgM and beta 1C/beta 1A were assessed as to their histological distribution in the trophoblastic tissues (TrT) by direct immunofluorescence technique. In the sera, they were determined by single radial immunodiffusion. Whole C titer (CH50) was also assayed in the sera by Kabat's method. The following results were obtained: 1. IgG was noted in granular pattern on the surface of syncytiotrophoblasts (STr) in NP-1, but it was rarely found on Tr in SpA. On the other hand, IgM was not usually observed in NP-1, but it was usually found in linear pattern on the surface of STr in SpA. Furthermore, beta 1C/beta 1A globulin was observed in the cytoplasm of STr in SpA, while it was not found in STr, but found in the basement membrane and/or fibrinoid areas of TrT in NP-1. 2. IgG and IgM in the sera gave no significant difference between SpA and NP-1. CH50, however, showed significant decrease (41.2+/- 5.4) in SpA (N = 16) compared to that (51.8 +/- 8.5) in NP-1 (N = 26). Serum beta 1C/beta 1A globulin level was also lower (53.0 +/- 8.4) in SpA (N = 22) compared to tha (60.5 +/- 14.8) in NP-1 (N = 30). The results lead us to the conclusion that humoral immune cytotoxicity by IgM in cooperation with C may be involved in the mechanisms responsible for the damage of Tr in SpA.