These cells are of lymphoid origin22 and are characterized by their rapid production of IL-5 and IL-13 in response to IL-25 and IL-33.17,19,20 Importantly, IL-33–driven type 2 ILCs were recently shown to contribute to AHR after viral infection and in protease-, ovalbumin-, and glycolipid–induced murine models of airway inflammation.23-28. This evidence concerns the gene IL25 and viral infectious disease.