Upregulation of CD11b on the surface of human eosinophils, which is associated with cell activation, is induced by stimulation with IL-3, GM-CSF, IL-5, IL-33, or eotaxin-1, among others, and is observed on eosinophils obtained from patients during the allergy season or in response to segmental or whole-lung antigen challenge [reviewed in (44)]. Here, IL33 is linked to allergic disease.