IL4 and asthma: In asthma, there exists selective expansion of T lymphocytes (particularly of TH2 cells) that secrete a cluster of cytokines such as interleukins (IL)-2, IL-4, IL-5, IL-9, and IL-13 and granulocyte-macrophage colony-stimulating factor (GM-CSF), leading to mast cell differentiation and maturation, eosinophil maturation and survival, basophil recruitment, B cell differentiation, and production of IgE, which jointly orchestrate the allergic inflammatory cascade [2, 3].