Activation of signaling pathways and prevention of apoptosis by cytokines in eosinophils

Inhibition of apoptosis in eosinophils by cytokines such as IL-5 and GM-CSF may play an important role in the pathogenesis of allergic and parasitic disorders. Recently there has been some progress in the understanding of the signal transduction pathways activated by these cytokines in eosinophils. The IL-3, IL-5 and GM-CSF receptors share a common signal transducer that possesses no intrinsic kinase domain. It has been shown that eosinophil stimulation by these cytokines is associated with increases in tyrosine phosphorylation of several cellular substrates. 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 receptor beta-subunit in eosinophils. This review will concentrate on this topic and on its role for the regulation of eosinophil apoptosis.