Interferon-γ Increases CD62L Expression on Human Eosinophils

<i>Background:</i> L-selectin (CD62L) and Mac-1 (CD11b/CD18) play a crucial role in the infiltration of eosinophils. However, changes in CD62L and CD11b expression on eosinophils after stimulation with cytokines were little studied. <i>Methods:</i> Eosinophils in peripheral blood of healthy volunteers were purified and cultured with interleukin-5 (IL-5), granulocyte/macrophage colony-stimulating factor (GM-CSF) or interferon-γ (IFN-γ). 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-γ-stimulated eosinophils were also studied. <i>Results:</i> IL-5 or GM-CSF downregulated CD62L and upregulated CD11b expression on eosinophils after 30 min stimulation. Conversely, IFN-γ 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 decreased CD62L expression on IFN-γ-stimulated eosinophils. <i>Conclusions: </i>IFN-γ is a particular cytokine which can increase CD62L expression on circulating or infiltrated human eosinophils. It is suggested that protein synthesis and intracellular cAMP participate in the increase in L-selectin expression on IFN-γ-stimulated eosinophils.