IL-5 is a cytokine that plays a key role in the activation, differentiation, chemotaxis, and survival of eosinophils.27, 28 Together with the cytokines IL-4 and IL-13, it is a typical marker of type 2 inflammatory response, and it is increased in most patients with CRSwNP. The gene discussed is IL5; the disease is chronic rhinosinusitis with nasal polyps.