Disconnect between sputum neutrophils and other measures of airway inflammation in asthma

To the Editor: Asthma heterogeneity has been described by the nature and intensity of granulocytic infiltration into the airways [1, 2]. Sputum, endobronchial biopsies and bronchoalveolar lavage (BAL) sample different anatomical regions of the airways. Few studies have directly compared the inflammatory cell infiltrates in these regions within a large cohort of moderate-severe asthma patients using standard techniques.