Specific cytotoxicity of antibody to YAL-198, a sperm antigen peptide, to murine zygote

Active immunization with the peptide segments rSMP-230 and YAL-198, corresp onding to the hydrophilic extracellular domain of two human sperm antigens (rSMP-B and YWK-II, respectively), reduced fertility in female rats by diff erent mechanisms. The anti-rSMP-230 antibody interferes with human and muri ne fertilization, and the anti-YAL-198 antibody blocks the development of m ouse embryos. The authors examined in vitro at which stage the antibodies t o rSMP-230 and YAL-198 were cytotoxic to murine embryos up to morula/blasto cyst stage. Anti-rSMP-230 antibody was not cytotoxic to any stages. On the other hand, the anti-YAL-198 antibody arrested the growth of embryos at the 2-cell stage but not at more advanced developmental stages. When the anti- YAL-198 antibody was used, spotty staining was observed only on the surface s of embryos that had arrested at the 2-cell stage. Unstained embryos, howe ver, continued to develop normally. In contrast, the anti-rSMP-230 antibody stained marine sperm but failed to stain murine ova and embryos. The prese nt results Suggest that the human sperm components rSMP-B and YWK-II play i mportant roles in sperm-egg interaction and early development of the embryo , respectively.