Immunofluorescent studies of the endometrial arteries in the first trimester of pregnancy.

Endometrial spiral arteries from curetted endometrium of 110 first-trimester pregnancies were studied by immunofluorescent (IF) technics using antibodies against human G, M, and A immunoglobulins, C3, C4, and fibrinogen. Heavy deposition of C3 in the arterial walls was found in 16 (14.6%) cases. Immunoglobulins, C4, and fibrinogen were found in only a few cases, and their staining was weak and not considered in this study. There was also a statistically significant (P less than 0.01) higher deposition of C3 in arterial walls of primipara (14 of 52), as compared to multipara (2 of 58). The possible mechanisms of C3 deposition and the importance of the higher incidence of this deposition in primipara are discussed in relation to suggested immunologic pathogenetic alterations in preeclampsia.