As we have only recruited CF patients outside of an exacerbation, it seems logic that sputum IL-22 expression in these clinically stable patients would be even lower as observed in the study of Aujla et al. The observation that IL-22 was increased in lung tissue and lung lymphocytes of P. aeruginosa-infected patients with CF might suggest that IL-22 acts locally in the lung tissue, but is not produced into the airway lumen, in contrast to IL-17A. Here, IL17A is linked to cystic fibrosis.