Selective immunolabeling of early gestational cytotrophoblast and its neoplastic counterpart by the monoclonal antibody Ber-EP4.

This report presents preliminary observations on the distribution of an epithelial surface antigen in human trophoblastic cells studied with the monoclonal antibody Ber-EP4 by means of an immunoperoxidase technique. Three cases of gestational choriocarcinoma and 20 cases of both villous and extravillous trophoblast, including one complete hydatidiform mole and one exaggerated placental site, were examined with a panel of monoclonal antibodies against epithelial antigen (Ber-EP4), cytokeratin (AE1 and AE3), vimentin (VIM), carcinoembryonic antigen (CEA) and epithelial membrane antigen (EMA), as well as with polyclonal antibodies against the beta subunit of human chorionic gonadotropin (hCG), human placental lactogen (hPL) and placental alkaline phosphatase (P1AP). While, as anticipated, all currently defined trophoblastic cell lines expressed low molecular weight cytokeratin only first trimester cytotrophoblastic cells and their neoplastic counterpart were found to possess the epithelial antigen detected by Ber-EP4. This distinctive property of the cytotrophoblast declined rapidly after eight weeks of gestational age but persisted in second trimester molar tissue and was prominently displayed in choriocarcinoma. By identifying the presence of cytotrophoblastic cell lines in malignancy more reliably than can be achieved with conventional panels of hCG, hPL and P1AP, Ber-EP4 has potential diagnostic utility in gestational trophoblastic disease. Our findings also suggest that the monoclonal anti-CEA antibody may be helpful in distinguishing between syncytiotrophoblastic cells and non-reactive multinucleate cells of the intermediate trophoblast.