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* From North West Lung Centre, University of Manchester, South Manchester University Hospitals Trust, Manchester, UK.
Correspondence to: Lucy J. C. Smyth, PhD, NWLC, Wythenshawe Hospital, Southmoor Rd, Manchester M23 9LT, UK; e-mail: ljcsmyth{at}yahoo.co.uk
Abstract
Background: 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.
Objective: To compare T-regulatory cell numbers in the BAL from COPD patients, smokers with normal lung function, and healthy nonsmokers (HNS).
Methods: 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.
Results: 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.
Clinical implications: Chronic cigarette smoke exposure up-regulates airway CD4 regulatory cell numbers. Their function may be to control pulmonary inflammation.
Key Words: CD4CD25(bright) COPD smokers T-regulatory cells
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