Additionally segmental airway challenge with IL-4 has been reported to induce airway eosinophilia and airway hyperresponsiveness (AHR) within 24 hours [9]; gain-of-function allelic variants of the IL-4 and IL-4Rα genes impart an increased risk of asthma to carriers [10, 11]; and blocking IL-4Rα through administration of anti-IL-4Rα mAb has shown good efficacy in improving pulmonary function and decreasing exacerbations of human asthma in phase 2b trials [12]. This evidence concerns the gene IL4R and airway hyperresponsiveness.