IMMUNOHISTOCHEMICAL LOCALIZATION OF SERINE-PROTEASE INHIBITORS IN THEHUMAN PLACENTA

Proteases and their inhibitors play a pivotal role in developmental an d differentiative processes. In the present report we investigated the immunohistochemical localization of alpha 1-antitrypsin, alpha 1-anti chymotrypsin and inter-alpha-trypsin inhibitor in first trimester as w ell as in term human placentas. For this purpose polyclonal antibodies against these serine-protease inhibitors were used. All inhibitors we re expressed in the villous syncytiotrophoblast of first and last trim ester placentas. Placental fibrinoid was positively stained for alpha 1-antitrypsin and inter-alpha-trypsin inhibitor throughout gestation. alpha 1-Antitrypsin and alpha 1-antichymotrypsin showed a strong immun ostaining in the Hofbauer cells (first trimester and full term placent as). Extravillous cytotrophoblast was negative for the three protease inhibitors throughout gestation. The presence of the three inhibitors in the syncytiotrophoblast suggests a role in coagulative, invasive an d immunomodulatory processes. Fibrinoid, staining for alpha 1-antitryp sin and inter-alpha-trypsin inhibitor, could also have an important im munoprotective function. The presence of protease inhibitors in the Ho fbauer cells suggests an involvement of these cells in villous remodel ling and differentiative processes.