Human Gingival Fibroblast Production of Interferon

Three human gingival fibroblast cell lines were used to determine whether they could be induced by a synthetic RNA and super-induced by metabolic inhibitors to produce interferon (IFN-β). When established procedures were followed for human fetal or newborn skin fibroblast cell lines, the adult gingival fibroblasts produced comparable amounts of IFN-β. It was shown that the superinducers alone would not cause an IFN-β production response, and that the absence of serum in the production medium also inhibited the production of IFN-β. The effect of IFN-β on cell growth was carried out in T-flasks seeded with 105 HEp-2 cells. After one and two wk, the cells of triplicate control flasks and triplicate flasks containing various dilutions of the production media were enumerated to determine a cell multiplication inhibition (CMI) value. A correlation between the IFN-β content and the CMI effect, however, was not obtained, and it was concluded that other CMI agents, possibly more potent than the IFN-β, were being produced by the stimulated human gingival fibroblasts. Cell protein assays which gave a high ng/ cell protein content correlated with TEM micrographs which showed clusters of complex lysosomes, primarily in cells cultured in the IFN-β-containing nutrient. However, since commercial IFN-β initiated no such lysosomal response, it was further concluded that the complex lysosomes were due to CMI agent(s) other than IFN-β.