Expression of macrophage surface markers in induced sputum of patients with chronic obstructive pulmonary disease

The aim of our study was to evaluate cellular content in induced sputum in chronic obstructive pulmonary disease (COPD) in relation to the degree of airway obstruction, macrophage count, and phenotype. We compared the proportion of macrophages and cells expressing the following markers: CD11b, CD14, CD54, and CD71 in induced sputum obtained from patients with mild-to-moderate and severe COPD (n=29)], asymptomatic smokers (n=18), and nonsmokers (n=18). The differential cell count and macrophage phenotypes were examined in induced sputum by immunocytochemistry. We observed a greater proportion of neutrophils and eosinophils and an elevated macrophage count in patients with COPD and in smokers in comparison with nonsmokers. Macrophages in patients with severe airway obstruction were characterized by a significantly elevated expression of CD11b and CD14 markers. There were higher proportions of macrophages with expression of CD11b, CD14, CD54, and CD71 in induced sputum of smokers in comparison with nonsmokers. We concluded that macrophages are the cells involved in the inflammatory process caused by smoking in COPD. The macrophage phenotype with elevated CD11b and CD14 expressions was associated with severe airflow limitation.