NO DETECTION OF INTERFERON-GAMMA ACTIVITY DURING EARLY-PREGNANCY IN THE MOUSE

PROBLEM: Interferons (IFN) have been shown to be secreted by the trophectoderm of implanting embryos in different species, in particular ungulates. In the pig, a clear-cut IFN-gamma production, the role of which is unknown, was found in the trophoblast at implantation. A murine counterpart to these IFNs has not vet been identified. METHOD: Two sets of experiments were conducted to test the presence of IFN-gamma in the mouse conceptus. First. day 4 blastocysts were collected from Swiss mice and their antiviral activity measured in a microassay using mouse L 929 cells and vesicular stomatitis virus (VSV) in the presence or absence of anti-IFN-gamma antibodies. In a second set of experiments, uteri from Swiss mice on days 5.5 and 6.5 of pregnancy were flushed and the resulting fluids assayed in a specific and sensitive ELISA test. RESULTS: In the antiviral assay, no consistent IFN-like activity was found. The viral challenge also revealed a high susceptibility of mouse blastocysts to VSV infection. By ELISA, all but two samples (N = 75), whether on 5.5 or 6.5, were found negative. CONCLUSIONS: We conclude that in this rodent species IFN-gamma is most probably not involved in early maternal-fetal interactions.