Immunologic and Biologic Study of Human Chorionic Gonadotropin*

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Abstract
Seven antigens are demonstrable in commercial human chorionic gonadotrophin (HCG) preparations by immunoelectrophoresis. Five of the 7 antigens present are contaminants, lack gonadotrophic activity, and are common to HCG preparations and acetone precipitated urine extracts. HCG antisera after adsorption with non-pregnant urine extracts contain precipitating antibodies to 2 antigens unique to pregnancy urines and HCG preparations. Such antisera appear highly specific for pregnancy. The 2 antigens unique to pregnancy are dissimilar but share partial immunological identity by immunoelectrophoresis. The precipitating and hemagglutinating antibodies in HCG antisera are directed against these antigens. The antibodies that neutralize the gonadotrophic activity of HCG as tested in the rat are independent of precipitating and hemagglutinating activity in antisera prepared against three different commercial HCG preparations. Antibodies directed against biologically active HCG are detected with certainty only by neutralization experiments. Current immunological methods appear to be of questionable value in the detection, assay, and localization of biologically active HCG.