Recently, numerous studies analyzing patient samples and murine models have revealed that ILC2s produce large amounts of IL-5 and IL-13 in response to IL-33 and IL-25 and that the activation of ILC2s by IL-33-ST2-mediated signaling contributes to anti-helminth responses and to the development of various allergic diseases such as asthma, atopic dermatitis, allergic rhinitis, and chronic rhinosinusitis (10–12, 15, 16). Here, IL33 is linked to chronic rhinosinusitis.