There is evidence that Th2 immunity plays a crucial role in inflammation and airway hyper‐responsiveness (AHR) in mouse models of allergic asthma.2 Th2‐type cytokines such as interleukin (IL)‐4, IL‐5 and IL‐13 stimulate the production of allergen‐specific immunoglobulin (Ig) E in B cells and infiltration of eosinophils into the lungs. The gene discussed is IL4; the disease is allergic asthma.