Interferon-gamma increases CD62L expression on human eosinophils

Background: L-selectin (CD62L) and Mac-1 (CD11b/CD18) play a crucial role i n the infiltration of eosinophils. However, changes in CD62L and CD11b expr ession on eosinophils after stimulation with cytokines were little studied. Methods: Eosinophils in peripheral blood of healthy volunteers were purifi ed and cultured with interleukin-5 (IL-5), granulocyte/macrophage colony-st imulating factor (GM-CSF) or interferon-gamma (lFN-gamma). After up to 24 h incubation, CD62L and CD11b expression were examined using flow cytometry. The effects of dexamethasone (Dex), cycloheximide (CHX) or theophylline on CD62L expression on IFN-gamma-stimulated eosinophils were also studied. Re sults: IL-5 or GM-CSF downregulated CD62L and upregulated CD11b expression on eosinophils after 30 min stimulation, Conversely, IFN-gamma upregulated CD62L after 12 h stimulation in a time- and dose-dependent manner, and had no effect on CD11b expression. Dex, CHX or theophylline dose-dependently de creased CD62L expression on IFN-gamma-stimulated eosinophils. Conclusions: IFN-gamma is a particular cytokine which can increase CD62L expression on c irculating or infiltrated human eosinophils. It is suggested that protein s ynthesis and intracellular cAMP participate in the increase in L-selectin e xpression on IFN-gamma-stimulated eosinophils.