Human trophoblast interferons: Production, purification, and biochemical characterization

Abstract

Summary Stimulation of human first and third trimester trophoblast and syncytotrophoblast cultures with viruses (Sendai and Newcastle Disease virus) led to the production of a mixture of IFN-α subtypes and-β. The magnitude and compositions of the IFNs produced were dependent on the gestational age of the trophoblast, the type of inducer and the stage of differentiation of the trophoblast. The data obtained indicated that the first trimester trophoblast cultures produce 5-to 6-fold more IFNs than the third trimester trophoblast on per cell basis whereas syncytitrophoblast produced 2-fold more IFNs than the mononuclear trophoblast at term when challenged with viruses. The viruses induced different levels and compositions of IFN-α and -β in both first and third trimester trophoblast and syncytiotrophoblast cultures. Tandem high-performance affinity chromatography (HPAC) of the virusinduced trophoblast interferon (tro-IFN) preparations resulted in the isolation of IFN-α subtypes with molecular masses of 16 and 22 kDa and β with molecular mass 24 kDa on SDS-PAGE. The antiviral activity of the tro-IFNs were stable at pH 2.0 and a fraction of the tro-IFN-α and -β were demonstrated to be glycoproteins. The tro-IFNs showed different antiviral activities when assayed on human and heterologous bovine cell species. Tro-IFN-α subtypes protected both human and bovine (MDBK) cells from virus infection whereas tro-IFN-β showed a high degree of species specificity being only active in protecting the human cell types tested. The tro-IFN-α and -β inhibited the secretion of prostaglandin E 2 (PGE 2 ) in trophoblast cultures in vitro .