Expression of Th1 and Th2 immunoregulatory cytokines by human eosinophils

Besides cytotoxic mediators, human eosinophils can produce proinflammatory and anti-inflammatory cytokines, as well as growth factors and chemokines. The demonstration that eosinophils from patients could produce IL-5, IL-4 a nd IL-2 suggested their participation in the regulation of immune response. In the present work, we have examined the presence of Th1 (IFN-gamma, IL-2 ) and Th2 (IL-4, IL-5, IL-10 and IL-13) cytokines in eosinophils from patie nts or donors by intracellular flow cytometry, and by immunocytochemistry. Whereas almost 100% eosinophils expressed intracellular IFN-gamma, IL-2 and IL-10, the expression of IL-4, IL-5 and IL-13 is more variable and increas ed in patients versus donors. The differential release by eosinophils of Th 2 versus Th1 cytokines is suggested both by the decrease of the intracellul ar content after culture, restricted to IL-4, IL-5 and IL-13, associated wi th an accumulation of IL-4 and IL-5 in the presence of Brefeldin. These res ults indicate that, through the preferential release of Th2 cytokines, huma n eosinophils can participate in the polarization of the immune response.