The antigenicity of human chorionic gonadotrophin.

Abstract

Human chorionic gonadotrophin (HCG) is antigenic in rabbits when injected with Freund's adjuvant. The HCG used for immunization showed the presence of five antigens in the Ouchterlony plates against the homologous antiserum. Three of these antigens were common to human serum and one of these three to normal human urine. Rabbit antiserum to HCG absorbed with human serum did not form any antigen-antibody precipitin line with either normal human serum or normal human urine. It formed two precipitin lines with HCG. One ml. of the rabbit antiserum to HCG could inhibit even 150 I.U. of HCG as tested by the Aschheim-Zondek test in mice and ovarian hyperaemia test in rats. The absorbed antiserum could inhibit hormonal activity of HCG even when the antiserum and HCG were injected simultaneously at separate sites.