IL4 and asthma: Type 2 immunity plays critical roles in the pathogenesis of asthma, particularly in type 2–high asthma, as type 2 cytokines, such as IL-4, IL-5, and IL-13, are important drivers of many features of airway inflammation in the disease, including bronchoconstriction, airway eosinophilia, and IgE upregulation.