Currently, in both the Leuven and Newcastle lung transplant centers, we are observing lung transplant patients, who develop persistent, neutrophilic airway inflammation despite azithromycin therapy for more than 3-week duration (denominated PAN or persistent airway neutrophilia in the current paper) in the absence of submucosal demonstrable IL-17 T lymphocytes 27. The gene discussed is IL17A; the disease is polyarteritis nodosa.