Mouse Sperm Antigens that Participate in Fertilization. III. Passive Immunization with a Single Monoclonal Antisperm Antibody Inhibits Pregnancy and Fertilization in Vivo1

Publisher Website
Google Scholar
Abstract
Passive immunization was used to study the effect of antimouse sperm monoclonal antibodies on fertilization in vivo. The effects of two antibodies were compared in this investigation. One of them, M29, has been shown previously to localize to the equatorial segment of the sperm head and to inhibit mouse fertilization in vitro in a concentration-dependent manner. The second antibody, M2, binds to the same area of the sperm head, and also belongs to the M immunoglobulin class (IgM), but does not affect fertilization in vitro. Superovulated female mice received two antibody injections intraperitoneally (at the tiems of the pregnant mare''s serum gonadotropin and human chorionic gonadotropin injections) at concentrations of 0.5-4.0 mg of IgM or control IgG; animals were mated within 6-12 h of the hCG injection. Fertilization and concomitant establishment of pregnancy were reduced significantly, in a dose-dependent manner, only in those animals immunized with M29 IgM (e.g., 4 mg M29 IgM: 12.6% of 304 eggs fertilized; 4 mg M2 IgM: 96% of 192 eggs fertilized). Intraperitoneal administration of the antibodies did not depress superovulation levels nor oocyte viability. 125I-labeled M29 IgM was used to determine the amount of antibody present in the oviductal ampulla at the time of fertilization in passively immunized mice. Luminal M29 IgM was found to be a linear function of the intraperitoneal dose: 0.002-0.003% of the injected dose was present in the oviductal lumen 14-16 h post-hCG. When the inhibitory efficacy of M29 under in vivo conditions was compared to that under in vitro conditions (Saling, Irons and Waibel, this issue), a high degree of correspondence was found for the two experimental systems. These results, achieved using a monoclonal antibody that recognizes a single sperm epitope, suggest a possible basis for the development of a contraceptive vaccine employing specific sperm antigens that participate in the fertilization process.