IL-4, IL-5, IL-6, and IL-13 have been shown to maintain this cycle of allergic inflammation [68] with IL-4 promoting Ig isotype switching [69], IL-5 inducing eosinophil differentiation and migration [70], and IL-13 causing goblet cell hyperplasia and airway hyperresponsiveness [71,72]. Here, IL4 is linked to airway hyperresponsiveness.