Placental MHC class I antigen expression is induced in mice following in vivo treatment with recombinant interferon-gamma

Abstract Allogeneically pregnant mice (NFR/N (Swiss-derived) H 2 q × 57/ B 1 H 2 b ) were injected daily from day 11 to 18 of gestation with recombinant rat interferon-gamma (IFN-γ) and the effects on placental MHC antigen expression were evaluated by immunohistochemistry. The results demonstrated that a daily dose of 200,000 U/mouse induces a significant increase in placental MHC class I expression in the decidua and the basal zone spongiotrophoblast as well as the fetal mesenchyme, while the labyrinthine trophoblast was almost completely MHC negative. No significant induction of MHC class II antigen expression was observed in the placental tissue, with the exception of a few scattered cells. The MHC class II-inducing efficiency of the treatment protocol used was ascertained by staining maternal skin (ear), which proved to contain considerably elevated numbers of MHC class II-positive cells (mainly keratinocytes). The IFN-γ treated group showed a higher incidence of fetal resorptions than the corresponding controls, but this was probably due to a non-specific toxic effect of the treatment as none of the sera analysed contained detectable amounts of anti-paternal antibodies, no infiltrating lymphocytes were detectable on histological examination of placental sections, and most of the IFN-γ treated animals successfully completed their pregnancy.