A MONOCLONAL-ANTIBODY TO AN EARLY-PREGNANCY FACTOR-INDUCED SUPPRESSOR FACTOR (EPF-S-1) DISRUPTS IMPLANTATION IN MICE

PROBLEM: The importance of EPF during pregnancy has been established previously but the importance of the EPF-induced suppressor factor EPF-S-1 in pregnancy has to date been unaddressed. Investigations were therefore conducted in order to study this. METHOD: Monoclonal antibodies to EPF-S-1 were produced, and one antibody, designated R2T gamma, was characterized. Mated mice were passively immunized with R2T gamma and the effect on implantation determined. RESULTS: Characterization of anti-EPF-S-1 R2T gamma revealed that it cross-reacted with EPF-S-1 of different MHC restriction but not with EPF or EPF-S-2. When injected into mated mice on days 1 to 4, R2T gamma had no effect on pregnancy but when injections continued to day 5, pregnancy was affected; the number of embryos implanted on day 7 were significantly less than the number of corpora lutea counted, signifying embryonic loss. CONCLUSION: These studies show that anti-EPF-S-1 R2T gamma disrupts implantation in mice when injected on days 1 to 5 of pregnancy but not when injected on days 1 to 4, demonstrating that EPF-S-1 exerts its effects around the time of implantation.