Development of anti-human FSH antibody in a patient with isolated FSH deficiency.

Antibodies to human FSH were documented in the serum of a patient previously shown to have isolated FSH deficiency. These antibodies developed subsequent to the administration of a second course of Human Menopausal Gonadotrophins (Pergonal 500). Using the ammonium sulfate precipitation method, antibodies were detected in the first week after cessation of Pergonal 500 therapy. Characterization of the antibody showed that (a) it was associated with the IgG fraction of the patient's serum; (b) addition of excess Pergonal 500 lead to rapid dissociation of 125I-FSH binding to serum; (c) pituitary FSH (LER-1366) and 2nd IRP-hMG, but not Hartree human LH, displaced 125I-FSH tracer bound to serum and (d) there was no binding of tracer insulin, hGH and LH by serum. Antibody has remained detectable over a 5-month period of observation.