Immunologically mediated male and female reproductive failure

This chapter reviews the mechanisms that prevent the development of immunity to spermatozoa and describe the conditions that may abrogate these defenses. The first line of defense against the development of a spermspecific autoimmune response in men is the blood-testis barrier between the Sertoli cells. In addition, Sertoli cells form an immunologic barrier by actively phagocytosing and degrading sperm and residual products of spermatogenesis, which would be a major source of antigenic stimulation if absorbed. The barrier between the reproductive system and the immune system is less effective in the rete testis and in the ductuli efferentes, and so these sites are more accessible to cellular immune components. In guinea pigs and in rabbits-it was shown that immunization with spermatozoa had little effect on fertilization but resulted in a much greater incidence of postfertilization embryonic loss. Studies show that there are three mechanisms by which antisperm antibodies can affect embryo survival. The first mechanism consists of the possibility that sperm surface antigens are incorporated into the zygotic membrane at fertilization. The second mechanism proposed is that similar epitopes are present on spermatozoa and embryos.