title: Correlation between exhaled nitric oxide, sputum eosinophils, and methacholine responsiveness in patients with mild asthma.
abstract: BACKGROUND
  Eosinophils in induced sputum and exhaled nitric oxide (NO) are currently used as non-invasive markers in the assessment of airway inflammation in asthma. As both sputum eosinophils (%) and exhaled NO are raised in asthmatic subjects not receiving inhaled steroids and decreased following corticosteroid therapy, a relationship between them is plausible.
  
  
  METHODS
  Exhaled NO was measured by chemiluminescence analyser, sputum induction by 3.5% saline inhalation, and bronchial responsiveness was measured as PC20FEV1 methacholine in 35 stable asthmatic patients using beta 2 agonist alone and the correlation between these non-invasive markers of airway inflammation was studied.
  
  
  RESULTS
  There were significant correlations between exhaled NO and PC20 (r = -0.64), exhaled NO and sputum eosinophils (%) (r = 0.48), and also between sputum eosinophils (%) and PC20 (r = -0.40).
  
  
  CONCLUSIONS
  The correlation between exhaled NO and PC20 suggests that exhaled NO or the mechanisms leading to its increase may contribute to airway hyperresponsiveness in asthma. Furthermore, the relationship between sputum eosinophils (%), exhaled NO, and PC20 highlight the potential use of eosinophils (%) in induced sputum and exhaled NO to monitor the severity of asthma.
authors.affiliation: Department of Thoracic Medicine, National Heart and Lung Institute, Imperial College, London, UK.
authors.forename: A
authors.initials: A
authors.lastname: Jatakanon
authors.forename: S
authors.initials: S
authors.lastname: Lim
authors.forename: S A
authors.initials: SA
authors.lastname: Kharitonov
authors.forename: K F
authors.initials: KF
authors.lastname: Chung
authors.forename: P J
authors.initials: PJ
authors.lastname: Barnes
mesh_terms: D000328:Adult; D001249:Asthma / Q000175:diagnosis* / Q000276:immunology / Q000503:physiopathology; D015415:Biomarkers / Q000032:analysis; D001798:Blood Proteins / Q000032:analysis; D001944:Breath Tests; D001985:Bronchial Provocation Tests; D003430:Cross-Sectional Studies; D047091:Eosinophil Granule Proteins; D004804:Eosinophils; D005260:Female; D006801:Humans; D007958:Leukocyte Count; D008163:Luminescent Measurements; D008168:Lung / Q000503:physiopathology; D008297:Male; D016210:Methacholine Chloride; D009569:Nitric Oxide / Q000032:analysis*; D011237:Predictive Value of Tests; D012129:Respiratory Function Tests; D012260:Ribonucleases; D013183:Sputum / Q000737:chemistry / Q000276:immunology*; D018709:Statistics, Nonparametric
chemical_list: D015415:Biomarkers; D001798:Blood Proteins; D047091:Eosinophil Granule Proteins; D016210:Methacholine Chloride; D009569:Nitric Oxide; D012260:Ribonucleases