Synthesis of cytokines by eosinophils and their regulation

Abstract

In addition to cytotoxic and proinflammatory mediators, eosinophils can produce a variety of cytokines and growth factors. Besides interleukin (lL)-5, we show in the present work that human eosinophils can synthesize interferon (IFN)-γ and IL.-10, by RT-PCR. in situ hybridization and immunostaining. Double-labelling procedures revealed the coexpression of IL-5 and IL-10 but not IL-5 and IFN-y, indicating the existence of subpopulations of eosinophils expressing type 1 or type 2 cytokines. IFN-α efficiently used for the treatment of hypereo-sinophilic syndromes can significantly decrease eosinophil degranulation and IL-5 release by eosinophils, through binding to a receptor for IFN-α. Thus, eosinophils can represent major sources of cytokines with regulatory functions, especially in allergic diseases and parasitic infections. © 1995 S. Karger AG, Basel.