HUMAN TROPHOBLAST INTERFERONS

The human placental trophoblasts which constitute the first fetal cell s and form the major cell layer of the feto-maternal interface are pot ent producers of interferons (IFNs). The IFN production is dependent o n the gestational age of the trophoblast, type of inducer and the stag e of differentiation of the trophoblasts. First trimester trophoblast populations produce higher levels (5-6 times) of IFN than the third tr imester trophoblasts when stimulated with viruses. Non-viral inducers, such as poly(rl).poly(rC), induce exclusively IFN-beta whereas viruse s such as Sendai and Newcastle Disease Virus (NDV) induce mixtures of IFN-alpha subtypes and IFN-beta. Differentiation of mononuclear cytotr ophoblasts into syncytiotrophoblasts in vitro increase the IFN product ion. High-performance and immunoaffinity chromatography of the virus-i nduced trophoblast IFN preparations resulted in the isolation of three antigenically distinct IFNs, namely, alpha(I), alpha(II)1 (omega 1), and beta with molecular masses of 16, 22 and 24 kDa, respectively, on SDS-PAGE. The human trophoblast IFNs have physical and antiviral activ ities characteristic of the Type 1 IFNs. The possible roles of the tro phoblast IFNs in human placental and fetal development are also discus sed in this review.