[6–10] Furthermore, higher concentrations of IL-5, IL-9 and eotaxin and more eosinophils and lymphocytes have been shown in bronchial biopsies and lavages from CRSwNP patients with asthma or airway hyperresponsiveness (AHR) compared with CRSwNP patients without asthma or AHR. Here, IL9 is linked to asthma.