Increased apoptosis of neutrophils in induced sputum of COPD patients

SummaryAimThe aim of the current study was to evaluate apoptosis in induced sputum neutrophils and to investigate the relationship between the number of apoptotic cells and clinical parameters in COPD patients.MethodsTwenty-four COPD ex-smoker patients and 10 healthy controls were included in the study. All subjects underwent clinical evaluation and sputum induction. Sputum cell in situ apoptosis was identified using white light microscopy and TUNEL assay technique. Apoptosis of neutrophils obtained by sputum induction was expressed as apoptotic rate (AR = percentage of apoptotic neutrophils over the number of neutrophils measured).ResultsTUNEL assay revealed statistically significant higher AR in COPD patients than controls (p = 0.004). Patients with FEV1 < 50%pred had significantly higher median (IQR) AR (%) compared to patients with FEV1 ≥ 50% [26.3 (16–29) vs 13.1 (8.6–21), p = 0.01]. No significant association was found between the number of apoptotic cells and age, symptoms or medication used.ConclusionThe significantly increased apoptotic rate of neutrophils that were found in COPD patients with advanced disease compared to controls might reflect either a deregulation of apoptosis of neutrophils or, a reduced clearance of apoptotic neutrophils from the airways. The pathophysiologic significance of the observed phenomenon has to be further explored.