EOSINOPHILS EXPRESS A FUNCTIONAL RECEPTOR FOR INTERFERON-ALPHA - INHIBITORY ROLE OF INTERFERON-ALPHA ON THE RELEASE OF MEDIATORS

Recent reports describe the beneficial use of alpha interferon (IFN al pha) for the treatment of idiopathic hypereosinophilic syndrome (HES) unresponsive to conventional therapy, A clinical improvement associate d with a rapid decrease of peripheral blood eosinophilia suggested pos sible direct effects of IFN alpha on eosinophils through the presence of IFN alpha receptors (IFN alpha R). Reverse transcriptase-polymerase chain reaction (RT-PCR) and cytochemistry were used respectively to d etect the presence and define the distribution of IFN alpha R on enric hed eosinophil preparations purified from blood cells. IFN alpha R was found on eosinophils collected from patients with various eosinophili c disorders. In addition, IFN alpha inhibited the release of eosinophi l granule proteins such as eosinophil cationic protein (ECP), neurotox in (EDN), or interleukin-5 (IL-5), Moreover, antiparasite cytotoxicity was also strongly reduced in a dose-dependent manner by IFN alpha. Th ese results provide the first evidence that human eosinophils express a functional receptor for IFN alpha and represent a potential basis fo r the beneficial effects of IFN alpha in patients with hypereosinophil ic syndromes. (C) 1996 by The American Society of Hematology.