Résumé
Monoclonal antibody, (mAb) D7G3, directed to human spermatozoa and cross-reactive with mouse and rat spermatozoa was found to be a sperm agglutinating antibody. It reacted with antigen present on the post acrosomal region of human spermatozoa and acrosomal region of mouse spermatozoa. The antigen reacting with mAb D7G3 was localized in mouse testicular germ cells and Sertoli cells. It was also localized in the epithelium and spermatozoa of the caput, corpus and cauda epididymides. In addition, the antigen was detected in the epithelial cells and secretions of the prostate and seminal vesicle. The mAb D7G3 reacted with a band of molecular mass 16 kDa in testicular and epididymal sperm and protein preparations of ventral prostate. In the seminal vesicle, an additional band of molecular mass 36 kDa was also identified. The effect of castration on the expression of proteins was studied in the rat. Immunohistochemical localization and Western blotting experiments showed that the antigens identified by the mAb D7G3 was detectable in the epididymis, ventral prostate and seminal vesicle after two weeks of castration. In the seminal vesicle, three additional bands were identified by mAb D7G3 following castration. The expression of this antigen throughout spermatogenesis and sperm maturation indicated that it may have an important biological function. A polyclonal antiserum directed to the 16 kDa mouse epididymal sperm protein was raised in rabbits. Passive immunization of female mice with this antibody caused a significant reduction in fertility only if administered 24 hours prior to mating, indicating that the antibody inhibited a pre-fertilization event by inhibiting sperm function.