IL4 and asthma: Interleukin (IL)-4, IL-5, and IL-13, which are canonical type 2 cytokines produced by TH2 cells, prominently mediate the development of asthma and airway inflammation, manifesting as enhanced IgE-mediated sensitization, airway hyperreactivity (AHR), as well as eosinophil infiltration (1, 10).