The immunobiology of follicle-stimulating hormone and inhibin: prospects for a contraceptive vaccine

Abstract

This review of the immunobiology of FSH and inhibin in animal research studies emphasizes unique behaviors of their antibodies potentially applicable to contraceptive vaccines. FSH is a di-peptide with an alpha subunit shared by LH and FSH but a beta subunit that determines the hormones biological action. Antibodies raised against ovine FSH in primates have induced temporary luteal inadequacy when passively transferred on specific days of the cycle. These antibodies are unusual for having different biological activity from that estimated from Scatchard plots of binding affinity. FSH antibodies passively administered to male primates have the potentially useful ability to cause temporary testicular dysfunction without compromising testosterone secretion of libido. Antibodies against intact FSH blocked FSH receptors markedly better than those raised against the beta subunit. Another unusual feature was that boosters with ovine FSH were less effective in monkeys that are boosters with heterologous FSH either human or pork. Inhibin is also a di-peptide synthesizes by luteal or Leydig cells that regulates FSH synthesis and secretion. Inhibin antiserum increases circulating FSH a connection that is being investigated for increasing ovulatory rates in sheep and cattle. Inhibin is also made in the prostate. Antibodies against human inhibin cause sperm agglutination and raise the FSH level in male rats enough to reduce sperm counts. Much more basic research on this peptide apparently released by at least 2 sites in the male is needed before contraceptive vaccines can be developed.