IMMUNOCYTOCHEMICAL LOCALIZATION OF HUMAN CHORIO-GONADOTROPIN IN HUMAN-MALIGNANT TROPHOBLAST - MODEL FOR HUMAN CHORIO-GONADOTROPIN SECRETION

  • 1 January 1979
    • journal article
    • research article
    • Vol. 40  (3) , 391-398
Abstract
Human choriogonadotropin (HCG) and its subunits were studied immunocytochemically using a recently developed unlabeled antibody method. Factors influencing the antigenicity of HCG and its subunits were explored and optimum conditions were determined. HCG was successfully localized at the cellular level using paraffin-embedded tissues. Several antibodies to HCG or its subunits were evaluated for specificity using rigorous immunologic controls. This methodology was applied to placental tissue, in vitro choriocarcinoma and in vitro breast carcinoma. HCG.beta. and HCG.alpha. were localized in the syncytial trophoblast of 1st trimester placenta with cytotrophoblast cell islands and Langhans'' cells being negative. Conditions of stimulated and unstimulated HCG production were explored in the BeWo line of malignant trophoblast. Stimulation was accomplished by treatment with dibutyryl cyclic[c]AMP and theophylline for varying periods of time. Only 6% of the cells produced HCG.beta. and HCG.alpha. in the unstimulated condition. Stimulation increased this percentage to 70 and 18%, respectively, after 24 h of treatment. Ultrastructural localization showed that the mechanism of synthesis and secretion of HCG follows a pathway that is not as extensively developed as that of the pituitary hormones.