Antigonadotrophic profile of antisera against human gonadotrophin preparations. 1. Biological characterization of the antigens used for immunization.

Abstract

ABSTRACT Human chorionic gonadotrophin (HCG), human menopausal gonadotrophin (HMG) and human hypophysial gonadotrophin (HHG) preparations were assayed by two bioassay methods for their HCG or luteinizing hormone (LH) and follicle stimulating hormone (FSH) activities and by two bioimmunoassay techniques for their anti-HCG neutralizing and anti-FSH neutralizing potencies. The immunological activities measured by bioimmunoassays were expressed in anti-anti-units (AAU) according to Petrusz et al. (1971a). Seven of the HCG preparations tested showed a good correlation between their HCG, FSH-like and anti-FSH neutralizing activities. An increase of 1000 IU/mg in the specific HCG activity was usually associated with an increase of 1 IU equivalent of FSH-like activity and with an increase of 100 AAU of the anti-FSH neutralizing potency. Four HCG preparations did not contain any detectable FSH-like activity; also these preparations neutralized high amounts of anti-FSH antibodies. Two highly purified HCG preparations possessed a much lower anti-FSH neutralizing potency than was expected on the basis of their specific HCG activities. These observations seem to indicate that some of the components responsible for the cross-reaction with FSH can be removed from HCG preparations by physico-chemical methods. The anti-HCG neutralizing potencies of partially purified HCG preparations agreed fairly well with their biological activities. In highly purified HCG preparations the biological activity exceeded 2 to 5 times the anti-HCG neutralizing potency. The anti-FSH and anti-HCG neutralizing potencies of HMG preparations having FSH/LH ratios close to unity were very similar to their biological FSH and LH activities, respectively. One LH preparation, purified from HMG and lacking detectable biological FSH activity, exhibited a high anti-FSH neutralizing potency. The anti-HCG neutralizing and anti-FSH neutralizing activities of the two HHG preparations tested were some 3 to 5 times more than their biological LH and FSH activities, respectively. It is concluded that the biological purity of human gonadotrophin preparations has little relevance to their immunological purity.