Antisperm antibodies associated with infertility: Properties and encoding genes of target antigens

Infertility among couples of reproductive age is a perplexing condition when the cause is indeterminate. These cases are classified as unexplained infertility. In a subset of subjects, antisperm antibodies with sperm agglutinating and/or immobilizing activities have been detected in the blood or fluids of the reproductive tract. These cases are designated as immunologic infertility although a cause and effect relationship of the antibodies to infertility has not been established. In this review, seven target sperm antigens to antibodies associated with infertility and their encoding genes are described. The antisperm antibodies (ASAs) examined were obtained from infertile women or were monoclonal antibodies (mAb) raised against human sperm proteins. All the ASAs studied possessed potent sperm agglutinating and/or immobilizing activities. The target antigens were isolated from human and other mammalian sperm, and the encoding genes identified. The seven antigens are YWK-II, BE-20, rSMP-B, BS-63 (nucleoporin-related), BS-17 (calpastatin), HED-2 (zyxin), and 75- kDa. Each antigen is a distinct and separate entity and is produced by different cells of the reproductive tract, (e.g., germ cells, epididymal epithelial cells, and Sertoli cells). No single predominant target component has been found to interact with the ASAs. It is proposed that immunologic infertility is the consequence of the combined actions of multiple ASAs in immobilizing and/or agglutinating spermatozoa, blocking sperm-egg interaction, preventing implantation, and/or arresting embryo development.