Signal Transduction through Interferon–Gamma Receptor on Human Eosinophils

Background: We reported on the constitutive interferon–γ receptor (IFN–γR) expression on eosinophils. But signal transduction through IFN–γR on eosinophils remains to be elucidated. In this study, we examined the involvement of the Jak/Stat pathway in the signaling of eosinophils after IFN–γR conjugation by the ligand binding. Methods: Purified peripheral eosinophils were stimulated with IFN–γ at 37°C for 1–60 min. Tyrosine phosphorylation of IFN–γR, Jak1, Jak2, and Stat1α was examined by immunoblotting. Gel–shift assay was also examined to show the formation of Stat1α–DNA complexes. Results: We show that binding of IFN–γ to human eosinophils initiated a series of events that resulted in the rapid tyrosine phosphorylation of not only the IFN–γRα chain but also Jak1, Jak2, and Stat1α. In addition, IFN–γ enhanced the DNA–binding activity of Stat1α. Conclusion: These data indicate that IFN–γ affects eosinophils through its specific receptor and utilizes the Jak/Stat pathway as its mode of signaling.