title: Interleukin-18 in induced sputum: association with lung function in chronic obstructive pulmonary disease.
abstract: BACKGROUND
  It has been shown that interleukin (IL)-18 levels in induced sputum are reduced in asthmatic and healthy smokers. However, in chronic obstructive pulmonary disease (COPD) patients, recent data show an overproduction in the lungs and increased serum levels of IL-18, suggesting that IL-18 may be involved in the pathogenesis of COPD.
  
  
  METHODS
  In order to assess the relation of IL-18 with pulmonary function and airway inflammation in COPD, IL-18, tumour necrosis factor-alpha, and IL-8 levels were measured by ELISA in sputum supernatants obtained from patients with bronchitis type COPD (n=28), and healthy subjects (18 smokers and 17 non-smokers). Cellular localization of IL-18 was assessed by immunocytochemistry.
  
  
  RESULTS
  The levels of IL-18 were significantly higher in sputum supernatants of COPD patients compared to healthy smokers and non-smokers (p<0.05). IL-18 production was localized to sputum macrophages. IL-18 levels were inversely correlated with FEV(1) (% predicted) (r=-0.572, p=0.002) and FEV(1)/FVC ratio in COPD smokers (r=-0.608, p=0.001). No correlations were found between IL-18 levels and inflammatory markers studied in induced sputum obtained from COPD patients, healthy smokers and non-smokers.
  
  
  CONCLUSIONS
  In patients with COPD, increased levels of IL-18 in induced sputum were associated with airflow limitation, suggesting that IL-18 may be implicated in the pathogenesis of COPD.
authors.affiliation: Department of Respiratory Medicine, Medical School, University of Athens, Sotiria Hospital for Diseases of Chest, 152 Mesogion Avenue, Athens GR-11527, Greece. krovina@med.uoa.gr
authors.forename: Nikoletta
authors.initials: N
authors.lastname: Rovina
authors.forename: Efrossini
authors.initials: E
authors.lastname: Dima
authors.forename: Christina
authors.initials: C
authors.lastname: Gerassimou
authors.forename: Androniki
authors.initials: A
authors.lastname: Kollintza
authors.forename: Christina
authors.initials: C
authors.lastname: Gratziou
authors.forename: Charis
authors.initials: C
authors.lastname: Roussos
mesh_terms: D015415:Biomarkers / Q000378:metabolism; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D020382:Interleukin-18 / Q000378:metabolism*; D016209:Interleukin-8 / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000235:genetics / Q000378:metabolism* / Q000503:physiopathology; D012129:Respiratory Function Tests; D013183:Sputum / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D015415:Biomarkers; D020382:Interleukin-18; D016209:Interleukin-8; D014409:Tumor Necrosis Factor-alpha