Natural and induced immunological infertility

Given the observation that naturally occurring antibodies to eggs and sperm can cause infertility, it seems feasible to pursue development of an infertility vaccine based on the induction of a specific immune response to gamete or early embryo antigens. Antibodies directed to the zona pellucida have been researched, but at current levels of purification, result in reduced ovarian hormone production. Of the numerous sperm antigens, LDH-C4 appears most promising for use in a vaccine. In the past decade, antisperm antibody investigations have focused on surface antibodies and sperm mixed agglutination reactions. It appears that antibodies in accessory fluids bind to sperm during ejaculation and/or antisperm antibodies enter the male tract at the epididymal level or higher. Antibodies directed against egg or sperm may prevent or modify the normal process of capacitation in which sperm undergo a series of biochemical and morphological transformations. Antisperm antibodies can suppress fertility by preventing sperm transport through cervical mucus or impeding the sperm-egg interaction during fertilization. The definition of sperm antigens associated with infertility--essential for development of a contraceptive vaccine--is being facilitated by monoclonal antibody techniques and DNA technology. Since the sperm surface is organized into highly specialized and distinct regions, cell recognition is an important research area. Most salient to the recognition and regulation of cell interaction are the components of the sperm plasma membrane and the zona pellucida.