No Detection of Interferon‐γ Activity During Early Pregnancy in the Mouse

Abstract

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 yet been identified. 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. 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. We conclude that in this rodent species IFN-gamma is most probably not involved in early maternal-fetal interactions.