IL4 and allergic asthma: Classically, recruitment of CD4+ T helper 2 (Th2) cells has been considered integral to the development of eosinophil-mediated allergic asthma, because these cells produce pro-inflammatory cytokines, particularly interleukins 4 (IL-4), IL-5, and IL-13, which are responsible for IgE production, eosinophil infiltration, and mucus-producing cell hyperplasia, respectively [11,12].