The evidence of IL-25-mediated Th2 cell differentiation, increase in production of IL-4, IL-5, and IL-13, elevated IgE and IgG levels, eosinophil infiltration, goblet cell hyperplasia and mucus hypersecretion, provided the proof for the role of IL-25 into asthma pathogenesis (88–90). This evidence concerns the gene IL5 and asthma.