Immunohistochemical interaction on antisera to HCG and its subunits with chorionic tissue of early gestation

Immunohistochemical localization of hCG and its subunits in chorionic tissue of early gestation was carried out. Antibodies to purified hCG and its subunits were obtained by using these agents for immunization according to the small doses method. The antibody titers and specificities were examined by B/T and standard curves in homologous radioimmunoassay system. The tissue preparations were stained both by a direct and by an indirect method utilizing these antisera and observing the specimens under a fluorescent microscope. The results were as follows. 1) With the anti-hCG staining, fluorescence was observed in the syncytiotrophoblasts as reported previously while the cytotrophoblast were stained slightly. 2) with the anti-hCG-beta staining, the fluorescence was almost identical with that of hCG and showed a more distinct pattern. 3) with the anti-hCG-alpha staining, the fluorescence was found both in the syncytio- and cytotrophoblasts concurrently. Fluorescence of the latter cells was recognized as due to free alpha-subunit because cytotrophoblast was scarcely stained with anti-hCG and anti-hCG-beta.