IL4 and allergic asthma: In asthmatic individuals, allergen exposure facilitates expansion of pathogenic, allergen-specific Th2 cells producing IL-4, IL-5 and IL-13, cytokines which induce pulmonary eosinophilic inflammation, IgE synthesis, airway wall remodeling and airway hyperresponsiveness (AHR), hallmarks of allergic asthma [1].