A NOVEL-APPROACH TO THE GENERATION OF ANTIBODIES AGAINST PHYLOGENETICALLY PRESERVED SPERM ANTIGENS

Conventional methods for immunization of laboratory animals against hu man spermatozoa proved not to be efficient enough to identify phylogen etically conserved sperm-specific antigens. A combination of vasectomy and subcutaneous administration of autologous testis homogenates was tested in 5 New-Zealand rabbits, and in 7 Long-Evans and 8 Spraque-Daw ley rats in an attempt to induce an autoimmune response against such a ntigens. This experimental procedure resulted in a generation of sperm autoantibodies cross-reactive with human, rabbit and rat spermatozoa, as demonstrated by sperm-agglutination, ELISA and flow cytometry (FCM ). No specific binding to human seminal plasma was detected by ELISA, indicating that intrinsic sperm membrane antigens rather than sperm-co ating antigens were involved in establishing cross-reactivity with hum an spermatozoa. This suggestion was confirmed by the finding that rabb it autoantisera reacted more strongly against epididymal than against ejaculated human spermatozoa as shown by FCM. Humoral antispermatozoal response correlated well with impaired spermatogenesis in rabbits. Th e autoimmunized rats revealed severe alterations in reproductive tissu es, including testicular and epididymal sperm granulomas; however, the y showed a lower incidence of circulating antibodies. The results indi cate that the established experimental model in rabbits can be further used to identify and characterize evolutionary preserved intrinsic sp erm membrane autoantigens, which are desirable candidates for contrace ptive vaccine development.