IL5 and asthma: Eosinophils, stimulated by IL-5,[28] can cause inflammation and the release of histamine.[29] Platelet-activating factor secreted by eosinophils increases mucosal secretion of leukotriene C4, oxygen free radicals, degranulation of eosinophils,[30] and aggravates asthma exacerbations, inflammation and local edema of nasal mucosa, and causes a decline in lung function.