Antiprothrombin autoantibodies in severe preeclampsia and abortion

PURPOSE: We examined the levels of autoantibodies against prethrombin-1 and fragment-1 in pregnant women to determine the type of autoantibodies that were associated with severe preeclampsia or spontaneous abortion. SUBJECTS AND METHODS: We measured autoantibodies bound to prothrombin, prethrombin-1, and fragment-1 by using an enzyme-linked immunosorbent assay (ELISA) in 12 healthy nonpregnant women, 36 women with normal pregnancies, 28 pregnant women with severe preeclampsia, and 19 pregnant women who subsequently had spontaneous abortion. RESULTS: Plasma samples in 10 (36%) of the 28 women with severe preeclampsia and 11 (58%) of the 19 women with spontaneous abortion were positive for antiprothrombin antibodies as compared with 3 (9%) of the 36 women with normal pregancies. All 11 of the positive samples from women who had spontaneous abortions were positive for antiprethrombin-1 antibody, but only 1 was positive for antifragment-1 antibody. The mean ( ± SD) titer of antiprethrombin-1 antibodies in patients with spontaneous abortion (36 ± 9 U) was higher than that in women with normal pregnancies (10 ± 4 U; P<0.01). Antiprethrombin-1 antibody was detected in only 2 women with severe preeclampsia, whereas all 10 women with antiprethrombin antibodies were positive for antifragment-1 antibody. The antifragment-1 antibody titer in patients with severe preeclampsia (49 ± 15 U) was higher than in women with normal pregnancies (13 ± 6 U, P<0.01). CONCLUSIONS: There is a strong and specific association between various types of antiprothrombin antibodies with severe preeclampsia and spontaneous abortion.