Intracellular localization of interleukin-6 in eosinophils from atopic asthmatics and effects of interferon γ

Paige Lacy, Francesca Levi-Schaffer, Salahaddin Mahmudi-Azer, Ben Bablitz, Stacey C. Hagen, Juan Velazquez, A. Barry Kay, Redwan Moqbel*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

81 Scopus citations


Eosinophils, prominent cells in asthmatic inflammation, have been shown to synthesize, store, and release an array of up to 18 cytokines and growth factors, including interleukin-6 (IL-6). In this report, we show that IL-6 immunofluorescence localizes to the matrix of the crystalloid granule in peripheral blood eosinophils from atopic asthmatics using confocal laser scanning microscopy (CLSM). Granule localization of IL-6 was confirmed using dot-blot analysis and enzyme-linked immunosorbent essay (ELISA) on subcellular fractions of highly purified eosinophils produced from density centrifugation across a 0% to 45% Nycodenz gradient. IL-6 was found to coelute with eosinophil crystalloid granule marker proteins, including eosinophil peroxidase (EPO), major basic protein (MBP), arylsulfatase B, end β-hexosaminidase. Immunoreactivity to IL-6 colocalized with granule- associated IL-2 end IL-5 in subfractionated eosinophils. We also made the novel end compelling observation that interferon γ (IFNγ), a Th1-type cytokine, stimulated an early elevation in eosinophil IL-6 immunoreactivity. A 2.5-fold enhancement of IL-6 immunoreactivity in eosinophil granules was observed within 10 minutes of IFNγ treatment (500 U/mL), as determined by subcellular fractionation and CLSM. These findings suggest that IFNγ has short-term effects on human eosinophil function and imply that a physiologic role exists for Th1-type cytokine modulation of Th2-type responses in these cells.

Original languageAmerican English
Pages (from-to)2508-2516
Number of pages9
Issue number7
StatePublished - 1 Apr 1998


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