Sperm Antigens, Immunologic Infertility and Contraception

Abstract

The demonstration at the turn of the century that sperm cells are antigenic and capable of eliciting autoantibodies initiated an era of experimentation which continues to expand. As early as the 1920’s speculation arose concerning the possible role of immunologic reactions involving sperm in human infertility.¹ Indeed, early studies in experimental animals suggested infertility could be induced in females by immunization with semen.² These reports surely stimulated the attempts that followed to immunized women by multiple injections of human semen. Whereas, the report on subcutaneous injections of semen in three women suggested a failure to induce serum antibodies to sperm,³ a more extensive study in 20 women injected by the intramuscular route reported induction of both antibody and infertility.⁴ The antibody detected was cytotoxic to sperm and appeared in the sera of all but one woman and in the cervical secretions of half the cases. No pregnancies were reported in the presence of serum antibody but, unfortunately, the short followup period did not permit adequate evaluation. However, this study definitely showed the iso-antigenicity of human sperm in women and that the concept of an immunologic contraceptive based on sperm antigens is plausible. During the same time frame the hypothesis was advanced suggesting that the occurrence of spontaneous antisperm antibodies in women could induce infertility. It was not until the 50’s and 60’s however, when several different groups of clinical investigators working with men and women of infertile couples reported that the evidence supported an association between human infertility and antibodies to sperm.^5,6,7