IL5 and eosinophilic granulomatosis with polyangiitis: This can be explained by the production of IL-4 and IL-13 by Th2 lymphocytes in addition to IL-5, further underlying the role of this cell subset in EGPA pathogenesis; however, it should be emphasized that high IgE serum levels are demonstrated in many allergic disease and are not a specific feature of EGPA [14].