Trophoblast interferon and pregnancy.

The maternal recognition of pregnancy in ruminants requires the production of interferons by the preimplantation blastocyst. These proteins, the trophoblast interferons (IFN-tau), are the products of a number of similar genes, the expression of which is controlled by characteristic promoter regions. They are expressed for a short period in high concentrations, and have antiluteolytic, antiviral, antiproliferative and immunomodulatory effects, through receptors on the endometrial epithelium. The antiluteolytic effects of IFN-tau result from inhibition of endometrial expression of the oxytocin receptor, through which circulating oxytocin stimulates episodic prostaglandin F2a production. Some of the properties of IFN-tau differ from those of other type I interferons, and they may have novel therapeutic effects. Because of their central role in early gestation, these proteins have excited the interest of reproductive physiologists. However, their other properties, and the fact that their expression is controlled so precisely, have made them of interest to a wide range of biologists.