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Signal transduction through interferon-gamma receptor on human eosinophils
K Ochiai1, C Ishihara, H Tomioka
1Internal Medicine and Pediatrics, Toho University School of Medicine, Sakura Hospital, Sakura, Japan.
Background:
We reported on the constitutive interferon-gamma receptor (IFN-gammaR) expression on eosinophils. But signal transduction through IFN-gammaR 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-gammaR conjugation by the ligand binding.
Methods:
Purified peripheral eosinophils were stimulated with IFN-gamma at 37 degrees C for 1-60 min. Tyrosine phosphorylation of IFN-gammaR, Jak1, Jak2, and Stat1alpha was examined by immunoblotting. Gel-shift assay was also examined to show the formation of Stat1alpha-DNA complexes.
Results:
We show that binding of IFN-gamma to human eosinophils initiated a series of events that resulted in the rapid tyrosine phosphorylation of not only the IFN-gammaRalpha chain but also Jak1, Jak2, and Stat1alpha. In addition, IFN-gamma enhanced the DNA-binding activity of Stat1alpha.
Conclusion:
These data indicate that IFN-gamma affects eosinophils through its specific receptor and utilizes the Jak/Stat pathway as its mode of signaling.