IL13 and asthma: From 70 to 80% of patients with corticosteroid naive asthma and 50% with corticosteroid-treated asthma are estimated to have an elevated sputum eosinophil count [78], which is generally associated with enhanced expression of the type-2 cytokines interleukin (IL) -4, IL-5, and IL-13 [79], increased fractional exhaled nitric oxide (FeNO), and peripheral blood eosinophilia.