CD4-Regulatory Cells in COPD Patients

The numbers of airway CD8 and B lymphocytes are increased in COPD patients, suggesting an autoimmune process. CD4-regulatory T cells control autoimmunity but have not been studied in patients with COPD. To compare T-regulatory cell numbers in the BAL from COPD patients, smokers with normal lung function, and healthy nonsmokers (HNS). BAL and peripheral blood mononuclear cell (PBMC) samples were obtained from 26 COPD patients, 19 smokers, and 8 HNS. Flow cytometry was performed for regulatory phenotypic markers. COPD patients had increased BAL CD8 numbers compared to smokers and HNS. CD4 numbers were similar between groups. There was increased BAL CD4CD25(bright) expression in smokers (median 28.8%) and COPD patients (median 23.1%) compared to HNS (median 0%). Increased FoxP3 expression was confirmed in BAL CD4CD25(bright) cells. BAL CD4CD25 cells expressed less CD27 compared to PBMCs, suggesting weaker functional regulatory ability. Chronic cigarette smoke exposure up-regulates airway CD4 regulatory cell numbers. Their function may be to control pulmonary inflammation.