Intermediate filaments of human trophoblast and choriocarcinoma cell lines.

Human term placenta and two human choriocarcinoma cell lines were studied immunohistochemically and by immunoblotting with monoclonal antibodies to keratin polypeptides and vimentin. Four keratin polypeptides (40, 45, 52, 54 K) were detected in both normal and malignant trophoblastic cells. The presence of the 54 K keratin polypeptide distinguishes the benign and malignant trophoblastic cells from human embryonal carcinoma cells and a yolk sac carcinoma cell line.