title: Cell recovery in bronchoalveolar lavage fluid in smokers is dependent on cumulative smoking history.
abstract: BACKGROUND
  Smoking is a risk factor for various lung diseases in which BAL may be used as a part of a clinical investigation. Interpretation of BAL fluid cellularity is however difficult due to high variability, in particular among smokers. In this study we aimed to evaluate the effect of smoking on BAL cellular components in asymptomatic smokers. The effects of smoking cessation, age and gender were also investigated in groups of smokers and exsmokers.
  
  
  METHODS
  We performed a retrospective review of BAL findings, to our knowledge the largest single center investigation, in our department from 1999 to 2009. One hundred thirty two current smokers (48 males and 84 females) and 44 ex-smokers (16 males and 28 females) were included. A group of 295 (132 males and 163 females) never-smokers served as reference.
  
  
  RESULTS
  The median [5-95 pctl] total number of cells and cell concentration in current smokers were 63.4 [28.6-132.1]×10(6) and 382.1 [189.7-864.3]×10(6)/L respectively and correlated positively to the cumulative smoking history. Macrophages were the predominant cell type (96.7% [90.4-99.0]) followed by lymphocytes (2% [0.8-7.7]) and neutrophils (0.6% [0-2.9]). The concentration of all inflammatory cells was increased in smokers compared to never smokers and ex-smokers. BAL fluid recovery was negatively correlated with age (p<0.001). Smoking men had a lower BAL fluid recovery than smoking women.
  
  
  CONCLUSIONS
  Smoking has a profound effect on BAL fluid cellularity, which is dependent on smoking history. Our results performed on a large group of current smokers and ex-smokers in a well standardized way, can contribute to better interpretation of BAL fluid cellularity in clinical context.
authors.affiliation: Division of Respiratory Medicine, Department of Medicine, Karolinska Institutet, Karolinska University Hospital Solna, Stockholm, Sweden. reza.karimi@ki.se
authors.forename: Reza
authors.initials: R
authors.lastname: Karimi
authors.forename: Göran
authors.initials: G
authors.lastname: Tornling
authors.forename: Johan
authors.initials: J
authors.lastname: Grunewald
authors.forename: Anders
authors.initials: A
authors.lastname: Eklund
authors.forename: C Magnus
authors.initials: CM
authors.lastname: Sköld
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D001992:Bronchoalveolar Lavage Fluid; D001999:Bronchoscopy / Q000379:methods; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008171:Lung Diseases / Q000139:chemically induced*; D008214:Lymphocytes / Q000166:cytology; D008264:Macrophages / Q000166:cytology; D008297:Male; D008875:Middle Aged; D009504:Neutrophils / Q000166:cytology; D012189:Retrospective Studies; D012307:Risk Factors; D012737:Sex Factors; D012907:Smoking; D016540:Smoking Cessation