ACTIVATION OF SIGNALING PATHWAYS AND PREVENTION OF APOPTOSIS BY CYTOKINES IN EOSINOPHILS

Inhibition of apoptosis in eosinophils by cytokines such as IL-5 and G M-CSF may play an important role in the pathogenesis of allergic and p arasitic disorders. Recently there has been some progress in the under standing of the signal transduction pathways activated by these cytoki nes in eosinophils. The IL-3, IL-5 and GM-CSF receptors share a common signal transducer that possesses no intrinsic kinase domain. It has b een shown that eosinophil stimulation by these cytokines is associated with increases in tyrosine phosphorylation of several cellular substr ates. In the past few years, there has been some progress in defining the tyrosine kinases that are activated by the IL-3/IL-5/GM-CSF recept or beta-subunit in eosinophils. This review will concentrate on this t opic and on its role for the regulation of eosinophil apoptosis.