IL-13 is produced by T cells and is important in the TH2 response. IL-13 targets include B cells, eosinophils, fibroblasts, mast cells and macrophages (1-3). IL-13 binds specifically to IL-13Rα1 that complexes with IL-4Rα to form the Type II IL-4R. Jak1 and Tyk2 are activated and signal through Stat3 and Stat6 (6). IL-13Rα2 is a different gene product, lacks the intracellular domain, does not complex with IL-4Rα and does not signal (1,6,7). The extracellular domain of IL-13Rα2 is often elevated in diseased states. IL-13 plays key roles in airway hyperresponsiveness (AHR) of allergic asthma (1,4,5) and modulates resistance to parasitic organisms (1).
