The European respiratory journal : official journal of the European Society for Clinical Respiratory Physiology
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CD4+CD25+ FOXP3-positive T-regulatory cells have an important role in controlling immune and inflammatory reactions. The present authors hypothesise that these cells may be involved in the pathogenesis of chronic obstructive pulmonary disease (COPD). The aim of the present study was to characterise the expression of FOXP3 in large and small airways of nonsmokers, smokers with normal lung function and COPD patients. ⋯ In small airways, COPD patients had decreased numbers of FOXP3-positive cells, compared with asymptomatic smokers and nonsmokers, that negatively correlated with airflow obstruction. To conclude, chronic obstructive pulmonary disease is characterised by upregulation of FOXP3-positive cells in large airways but a downregulation in small airways that correlated with airflow limitation. The results of the present study contribute to a better understanding of the pathogenesis of chronic obstructive pulmonary disease.