IL4 and asthma: To date, asthma has been classically associated with type 2 inflammation, characterized by high levels of immunoglobin E (IgE), eosinophils, fractional exhaled nitric oxide (FeNO), and cytokines frequently found in allergic responses including interleukin 4, 5, 13 and 9 (IL-4, IL-5, IL-13, IL-9).