RESUMO
A new approach to fertility regulation is the development of vaccines directed against human substances required for reproduction. Potential candidates for immunological interference include reproductive hormones, ovum and sperm antigens, and antigens derived from embryonic or fetal tissue. Several vaccines targeted at the beta chain of the human chorionic gonadotrophin molecule have reached the clinical trial state in Australia, Finland, India and Sweden, and the preliminary results are very encouraging. A prototype vaccine using the beta subunit of ovine luteinizing hormone seems effective in female primates. Contradictory effects on spermatogenisis in male primates have been observed by different researchers using follicle-stimulating hormone as an antigen. Both this and gonadotrophin-releasing hormone require further basic research. Immunological interference could also be aimed at a sperm production or maturation, or at sperm-ovum interaction in the female reproductive tract. The best characterized sperm antigen to date is LDH-C4, an isoenzime of lactic dehydrogenase. The identification of new sperm antigens is being aided by monoclonal antibody techniques. Another approach is to detect, and then mimic, the antisperm antibodies found in women and men with immunologically mediated infertility. Research on ovum antigens is focusing on the zona pellucida (ZP); anti-ZP antibodies