|Increased levels of markers of airway inflammation (e.g. PMNs or inflammatory cytokines in BAL or sputum)|
|Increased levels of markers of airway injury or inflammation in exhaled breath (e.g. increased acidity of exhaled breath condensate or increased FeNO in asthmatics)|
|Increased levels of blood markers of lung injury (e.g. 8-isoprostanes, club cell secretory protein)|
|Imaging evidence for lung injury or reduced lung volume|
|Reduced pulmonary gas exchange (e.g. DLCO, DLNO, PaO2, pulse oximetry)|
|Increased airways responsiveness to nonspecific challenge|
|Increased airways hyperresponsiveness in asthmatic patients|
PMN: polymorphonuclear leukocyte; BAL: bronchoalveolar lavage; FeNO: exhaled nitric oxide fraction; DLCO: diffusing capacity of the lung for carbon monoxide; DLNO: diffusing capacity of the lung for nitric oxide; PaO2: arterial oxygen tension.