INDUCTION OF INTERFERON γ IN HUMAN GINGIVAL FIBROBLASTS CHALLENGED WITH PHYTOHAEMAGGLUTININ

Interferon gamma (IFN-γ) is a potential immunoregulatory cytokine, which is secreted mainly by cells of immune origin. In this study, we examined the capacity of human gingival fibroblasts as non-professional immune cells to express IFN-γ messenger RNA (mRNA) and to produce the protein. Cultures of fibroblast cells were established from gingival biopsies from three children. The expression of mRNA for IFN-γ was studied by in situ hybridization, and the level of IFN-γ was determined by cell-released capturing ELISA. Treatment of the cells with phytohaemagglutinin (PHA) (2.5, 5.0, and 10μg/ml) increased the number of IFN-γ mRNA expressing cells and the protein production at 1, 6, and 24h. Non-stimulated cells did not reveal measurable levels of IFN-γ mRNA or the protein. The inflammatory cytokines interleukin 1β (IL-1β) (100pg/ml) and tumour necrosis factor α (TNFα) (10ng/ml) did not affect IFN-γ mRNA expression or protein production. Treatment of the cells with 1μM phorbol 12-myristate-13-acetate (PMA) stimulated IFN-γ mRNA expression but had no effect on IFN-γ protein production. We conclude that human gingival fibroblasts not only transcribe IFN-γ mRNA but also produce the IFN-γ protein in response to PHA. The finding that human gingival fibroblasts, produce the cytokine IFN-γ, further support the concept that these cells take an active part in the modulation of the inflammatory and immune response in the periodontal tissue.