title: Distribution of T-cell subsets in BAL fluid of patients with mild to moderate COPD depends on current smoking status and not airway obstruction.
abstract: BACKGROUND
  COPD is characterized by chronic inflammation. CD8+ T cells and CD4+ T cells have both been implicated in the inflammatory response. We investigated whether the lymphocyte and T-cell subpopulations in BAL differ between patients with COPD who are current smokers and those who are ex-smokers.
  
  
  METHODS
  Forty never smokers, 40 smokers with normal lung function, and 38 patients with COPD, GOLD (Global Initiative for Chronic Obstructive Pulmonary Disease) stage I-II (27 smokers and 11 ex-smokers) underwent BAL. Using flow cytometry, cells were analyzed from BAL and blood for T-cell subsets, B cells, natural killer cells, and natural killer T (NKT)-like cells. The differentiation status of CD4+ T cells was also determined.
  
  
  RESULTS
  Smokers with or without COPD had higher percentages of CD8+ T cells and NKT-like cells in BAL than did never smokers and ex-smokers with COPD. Most of the NKT-like cells were CD8+. In contrast, the percentages of CD4+ T cells were lower in the smoking than in the nonsmoking groups. In blood, the frequency of CD4+ T cells was increased in the two smoking groups. Current smokers also had increased numbers of activated (CD69+) naive and effector CD4+ T cells in BAL compared with nonsmokers, particularly in patients with COPD. In male smokers with COPD, the percentage of CD8+ T cells in BAL positively correlated with the number of cigarettes per day.
  
  
  CONCLUSIONS
  Current smoking status has a greater impact than airway obstruction on the distribution of T-cell subsets in BAL of patients with mild to moderate COPD. This fact must be considered when the role of T cells in COPD is evaluated. Our results stress the importance of subgrouping patients with COPD in terms of smoking.
authors.affiliation: Respiratory Medicine Unit, Department of Medicine Solna and Centre for Molecular Medicine, Karolinska Institutet, Karolinska University Hospital, Solna, Stockholm, Sweden. Electronic address: Helena.Forsslund@ki.se.
authors.forename: Helena
authors.initials: H
authors.lastname: Forsslund
authors.affiliation: Respiratory Medicine Unit, Department of Medicine Solna and Centre for Molecular Medicine, Karolinska Institutet, Karolinska University Hospital, Solna, Stockholm, Sweden.
authors.forename: Mikael
authors.initials: M
authors.lastname: Mikko
authors.affiliation: Respiratory Medicine Unit, Department of Medicine Solna and Centre for Molecular Medicine, Karolinska Institutet, Karolinska University Hospital, Solna, Stockholm, Sweden.
authors.forename: Reza
authors.initials: R
authors.lastname: Karimi
authors.affiliation: Respiratory Medicine Unit, Department of Medicine Solna and Centre for Molecular Medicine, Karolinska Institutet, Karolinska University Hospital, Solna, Stockholm, Sweden.
authors.forename: Johan
authors.initials: J
authors.lastname: Grunewald
authors.affiliation: Respiratory Medicine Unit, Department of Medicine Solna and Centre for Molecular Medicine, Karolinska Institutet, Karolinska University Hospital, Solna, Stockholm, Sweden.
authors.forename: Åsa M
authors.initials: ÅM
authors.lastname: Wheelock
authors.affiliation: Respiratory Medicine Unit, Department of Medicine Solna and Centre for Molecular Medicine, Karolinska Institutet, Karolinska University Hospital, Solna, Stockholm, Sweden.
authors.forename: Jan
authors.initials: J
authors.lastname: Wahlström
authors.affiliation: Respiratory Medicine Unit, Department of Medicine Solna and Centre for Molecular Medicine, Karolinska Institutet, Karolinska University Hospital, Solna, Stockholm, Sweden.
authors.forename: C Magnus
authors.initials: CM
authors.lastname: Sköld
mesh_terms: D000328:Adult; D000368:Aged; D000402:Airway Obstruction / Q000097:blood* / Q000150:complications; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood* / Q000150:complications; D012720:Severity of Illness Index; D012907:Smoking / Q000097:blood*; D016176:T-Lymphocyte Subsets