Immunologic and biologic study of human chorionic gonadotropin

Immunological methods have been used to meas-ure human chorionic gonadotropin (HCG) in nor-mal and pathological pregnancies (1-3). Immu-nohistological methods with the fluorescent anti-body technique have also been used to localize HCG in placenta and tumors (4, 5). The anti-sera used in the above studies were produced with HCG preparations that contained contaminants and, therefore, contained antibodies to a multi-plicity of extraneous antigens in addition to HCG. Antibodies to some contaminants can be re-moved from HCG antisera by adsorption with urine, serum, or their extracts (1, 3, 6). Previous studies, however, have demonstrated that absorp-tion methods probably do not make such antisera HCG specific (7). This investigation is concerned with the immunological characteristics of several commercial HCG preparations in an attempt to evaluate the reliability and validity of the HCG antisera previously employed (1-5). Seven antigens are demonstrable in commercial HCG preparations by immunoelectrophoresis. Five of these contaminating antigens are common to HCG and nonpregnant urine extract and can be demonstrated by immunoelectrophoresis and he-magglutination. HCG antisera after adsorption with normal male urine powder contain antibodies to two antigens unique to pregnancy urine extracts and urinary HCG preparations. These two anti-gens are dissimilar but share partial immunologi-cal identity by immunoelectrophoresis. Chro-matographic separation of HCG preparations into biologically active and inactive fractions has made it possible to evaluate the relationship between im-munological and biological activities. The two antigenic moieties unique to pregnancy are differ