A Study of Defensins in Bronchoalveolar Lavage Fluid in Patients with Diffuse Panbronchiolitis

Abstract

We estimated defensins, antimicrobial and cytotoxic peptides localized in azurophil granules of neutrophils, in bronchoalveolar lavage fluid (BALF) in patients with diffuse panbronchiolitis (DPB). BALF from DPB patients contained a higher concentration of defensins than those from patients with idiopathic pulmonary fibrosis and healthy volunteers. A significant correlation was observed between the concentration of defensins and the number of neutrophils, the concentration of interleukin-8 or neutrophil elastase in BALF of DPB patients. An immunohistochemical study of open-lung biopsy specimens from DPB patients showed a strong immunoreactivity for defensins in neutrophils and mucinous exudates in the airways and in the surface of bronchiolar epithelial cells. After treatment with macrolide antibiotics, significant reductions in the concentrations of defensins, IL-8 and neutrophil numbers in BALF of DPB patients were observed. These findings suggest that the lung injury in DPB could be caused by defensins released by neutrophils accumulated in the airways.