Immunization of female baboons with hapten-coupled gonadotropins.

Female baboons (papio anubis) were immunized with gonadotropin preparations that had been structurally altered by hapten-coupling and the effects of such immunizations upon the events of the menstrual cycle were observed. Antibodies were detected against the immunizing antigen within 3-5 weeks. Cross-reaction of antibodies to sulphanil-azo-human luteinizing hormone (LH), human chorionic gonadotropin and ovine LH with unaltered baboon LH was marked only during the first 8 weeks, the period of immunoglobulin M (IgM) abundance, then dropped sharply as the antisera shifted to nearly all IgG. This drop did not occur with monkey and baboon immunizations. Ovulation was disrupted for 2-3 months with human and ovine gonadotropin immunizations but sulphanil-azo-monkey or baboon LH caused anovulation for 4-8 months. A reduction of hormone secretion correlated with titers of cross-reactivity. This evidence suggested that hapten-coupling produced changes in gonadotropins with enhance their antigenicity and the cross-reactivity of antibodies raised to them.