Neutrophils Infiltrating Bronchial Epithelium in Chronic Obstructive Pulmonary Disease

In order to characterize neutrophil and eosinophil presence in the airways of patients with chronic obstructive pulmonary disease (COPD), bronchoscopy with bronchial washings and bronchial biopsies was performed in 12 smoking stable COPD subjects and 18 normal non-smoking control subjects. Bronchial biopsies were examined by light microscopy using plastic embedding and histochemical techniques to identify different cell types. Bronchial washing fluid of COPD patients was characterized by a predominance of neutrophils (P = 0.001), and a slight, but significant (P = 0.03), increase of eosinophil fraction. Subjects with COPD had higher number of neutrophils in the epithelium (P = 0.01), and eosinophils in the lamina propria (P = 0.01) than did control subjects. The thickness of reticular basement membrane was increased for COPD patients in comparison to control subjects (P = 0.01). The present study provides evidence of neutrophil infiltration both in bronchial washing and bronchial epithelium of patients with COPD, suggesting that the source of neutrophils in airway lumen may be the bronchial mucosa. Although less common than in asthma, airways of COPD subjects reveal eosinophil presence and airway remodelling.