IL4 and asthma: Asthma pathology is heterogeneous; a major subtype is type 2 (T2) high asthma, which is driven by T helper 2 (Th2) lymphocytes and T2 cytokines (IL-4 and IL-13), and is often associated with eosinophilia and elevated immunoglobulin E (IgE) (Hammad and Lambrecht, 2021).