Macrophages, neutrophils and tumour necrosis factor- α expression in bronchiectatic airways in vivo

Abstract

Bronchiectasis is increasingly being recognized as an inflammatory condition of the airways in which pathological permanent dilation occurs. We have obtained endobronchial biopsies in 14 patients with stable bronchiectasis and 15 control subjects. Airway neutrophils, macrophages and tumour necrosis factor- α (TNF α)-positive cells were stained with monoclonal antibodies and the densities of positive cells in the lamina propria were determined by using a computer image analyser. There was significantly higher neutrophil, macrophage and TNF α -positive cell densities in the lamina propria of bronchiectatic than control airways (P<0·001, P<0·001 andP =0·0002, respectively). Airway neutrophil density, in bronchiectasis but not in controls, correlated with TNF α -positive cell density (r=0·71, P=0·004). A significant correlation between airway macrophage and TNF α -positive cell densities was demonstrated in both control and bronchiectatic airways (r=0·63, P=0·016 and r=0·60,P =0·02 respectively). Neutrophil density negatively correlated with per cent forced vital capacity (FVC%) predicted among patients with bronchiectasis (r=−0·53, P=0·04). Bronchiectasis patients who were regular sputum producers had a significantly higher macrophage, but not neutrophil density, than their counterparts (P=0·02 and P=0·48 respectively). Our original findings suggest that airway macrophages could contribute to neutrophil influx into airway walls through their production of TNF α and therefore play an important role in the pathogenesis of bronchiectasis.