The cellular composition and macrophage phenotype in induced sputum in smokers and ex-smokers with COPD

Study objectives: The relationship between smoking and COPD has been well-documented. We investigated the impact of cigarette smoking on airway inflammation in COPD patients. Design: Changes in cell profiles in induced sputum (IS) samples from smokers with COPD and patients who ceased smoking were compared. Setting: Department of pneumonology in a university hospital. Patients: IS samples were collected from 17 smokers and 17 ex-smokers with COPD. Interventions: We examined IS samples for differential cell counts and macrophage phenotypes determined by immunocytochemistry with monoclonal antibodies anti-CD11b, anti-CD14, anti-CD54, and anti-CD71. Measurements and results: The median IS volume was greater and the total cell count was higher in smokers than in ex-smokers. The difference, however, was not significant. We did not find any significant differences in the proportions of cells and in the phenotypes of macrophages between the two groups, with the proportion of eosinophils being slightly higher in the group of smokers. We found, however, a significant positive correlation between the decrease in pulmonary function parameters and the number of pack-years smoked, an inverse correlation of pulmonary function test results with the number of lymphocytes in IS, and a correlation between some changes in the expression of macrophage surface markers and smoking history. There was no correlation between the time from smoking cessation and any cellular component found in IS samples. Conclusions: The analysis of IS samples in patients with COPD revealed no significant differences in cell count and macrophage phenotypes between active smokers and ex-smokers.