Expression of the antiviral protein Mx in peripheral blood mononuclear cells of pregnant and bred, non-pregnant ewes

Interferon-tau (IFN tau) acts locally on the endometrium to suppress estrog en and oxytocin receptor expression and block luteolysis in ruminants. Syst emic administration of conceptus homogenates or recombinant ovine IFN tau d oes not block luteolysis or enhance pregnancy rates in sheep or cattle, res pectively. However, IFN tau up-regulates expression of the antiviral protei n Mx throughout the entire uterine wall during early pregnancy. These studi es determined if conceptus-derived IFN tau also up-regulates Mx expression in components of the circulating immune system that migrate through the end ometrial wall. hi experiment one, peripheral blood mononuclear cells (PBMC) were isolated from ewes at D26 post-artificial insemination (Al) and Mx mR NA levels examined by Northern and slot-blot hybridization. Pregnancy resul ted in a two-fold increase in Mx mRNA levels compared to bred, non-pregnant ewes at D26. In experiment two, PBMC were isolated front ewes at Al, and e very three days from D9 to D30. Results showed a four-Cold increase in Mx m RNA levels in PBMC from pregnant versus bred, non-pregnant ewes at D15. Inc reased Mx mRNA, which remained elevated through D30, was accompanied by inc reased levels of Mx protein. These results show that pregnancy recognition signaling rapidly induces Mx gene expression in PBMC, and are the first to suggest that IFN tau activates gene expression in components of the circula ting immune system.