Human Eosinophils Constitutively Express a Functional Interleukin-4 Receptor: Interleukin-4 –Induced Priming of Chemotactic Responses and Induction of PI-3 Kinase Activity

Similar to interleukin-3 (IL-3), IL-5, and granulocyte macrophage colony-stimulating factor (GM-CSF), IL-4 can be secreted by several cell types involved in allergic inflammatory reactions, and therefore can affect eosinophil function similarly. In this study, we investigated the presence of an IL-4 receptor (IL-4R) on human eosinophils. When two different monoclonal antibodies (mAbs) against the IL-4R α-chain (IL-4Rα) were used, fluorescent-activated cell sorter analysis revealed the presence of an IL-4Rα on both eosinophils of normal donors and atopic dermatitis patients. In addition, the expression of the IL-2R γ-chain, a functional component of the IL-4R in some cell types, was demonstrated. The IL-4Rα appeared to be expressed constitutively, and stimulation with cytokines IL-2, IL-3, IL-5, GM-CSF, and interferon-γ did not further increase IL-4Rα expression. Evidence for an IL-4Rα was further substantiated by mRNA analysis. Both Northern blot analysis and reverse transcriptase/polymerase chain reactio...