SYNTHESIS OF CYTOKINES BY EOSINOPHILS AND THEIR REGULATION

In addition to cytotoxic and proinflammatory mediators, eosinophils ca n produce a variety of cytokines and growth factors. Besides interleuk in (IL)-5, we show in the present work that human eosinophils can synt hesize interferon (IFN)-gamma and IL-1O, by RT-PCR, in situ hybridizat ion and immunostaining. Double-labelling procedures revealed the coexp ression of IL-5 and IL-10 but not IL-5 and IFN-gamma, indicating the e xistence of subpopulations of eosinophils expressing type 1 or type 2 cytokines. IFN-alpha efficiently used for the treatment of hypereosino philic syndromes can significantly decrease eosinophil degranulation a nd IL-5 release by eosinophils, through binding to a receptor for IFN- alpha. Thus, eosinophils can represent major sources of cytokines with regulatory functions, especially in allergic diseases and parasitic i nfections.