Airway inflammation and hyperresponsiveness to adenosine 5′-monophosphate in chronic obstructive pulmonary disease

Abstract

Chronic obstructive pulmonary disease (COPD) is often accompanied by bronchial hyperresponsiveness (BHR). Measurement of BHR may give information about airway inflammation. To investigate the role of airway inflammation in hyperresponsiveness to adenosine 5′-monophosphate (AMP) in COPD. We investigated inflammatory indices in induced sputum, bronchoalveolar lavage (BAL) fluid and bronchial biopsies in subjects with COPD with and without hyperresponsiveness to AMP. Twelve nonatopic subjects with COPD with hyperresponsiveness to AMP (mean ± SD, age 63 ± 8 years, FEV₁% predicted 56 ± 13%), six without BHR (age 60 ± 6 years, FEV₁% predicted 65 ± 11%) and 11 healthy nonatopic controls without BHR (age 58 ± 8 years, FEV₁% predicted 104 ± 11%) participated in the study. Subjects with COPD with BHR had significantly higher numbers of mucosal CD8 + and higher percentages of sputum eosinophils than those without BHR (median, 550 cells/mm²; range, 30–1340 vs 280 cells/mm²; range, 110–450, P = 0.045; and median, 2.7%; range, 0.5–8.5 vs 0.6%; range, 0–0.8 %, P = 0.0036, respectively). No differences were observed in BAL fluid. We conclude that hyperresponsiveness to AMP in COPD is associated with airway inflammation that is characterized by increased numbers of mucosal CD8 + cells and percentages of sputum eosinophils. Hyperresponsiveness to AMP may be used as a marker of airway inflammation in COPD, but its significance in the clinical course remains to be determined.