ELANE and chronic obstructive pulmonary disease: Recently, NETs have been identified in the sputum of small numbers of patients with stable and exacerbating COPD through the use of confocal fluorescent and electron microscopy.14, 15, 16 In the study by Grabcanovic-Musija et al,14 COPD disease severity, as measured based on lung function, was associated with a greater amount of NET-associated neutrophil elastase determined by using confocal laser microscopy.