title: Effects of nitrogen dioxide on allergic airway responses in subjects with asthma.
abstract: OBJECTIVE
  We sought to determine whether nitrogen dioxide (NO2) can enhance airway inflammation after allergen challenge in asthmatic subjects.
  
  
  METHODS
  Fifteen house-dust-mite (HDM)-sensitive asthmatic subjects were exposed for 3 hours to filtered air or 0.4 ppm NO2, followed by inhalational challenge with HDM allergen. Markers of inflammation were measured in sputum at 6 hours and 26 hours after allergen challenge.
  
  
  RESULTS
  After exposure to NO2, eosinophil concentration decreased significantly in the 6-hour postallergen sputum. No significant NO2-related difference was observed for other variables.
  
  
  CONCLUSIONS
  Our results suggest that, in most asthmatic individuals, multi-hour exposure to a high ambient concentration of NO2 does not enhance the inflammatory response to subsequent inhaled allergen as assessed by cell distribution in induced sputum. Because the decrease in airway eosinophils has been reported in previous animal studies, future research should be directed toward the mechanism of this effect.
authors.affiliation: Lung Biology Center and Division of Occupational and Environmental Medicine, University of California, San Francisco, California 94143-0843, USA.
authors.forename: Allyson
authors.initials: A
authors.lastname: Witten
authors.forename: Colin
authors.initials: C
authors.lastname: Solomon
authors.forename: Emilio
authors.initials: E
authors.lastname: Abbritti
authors.forename: Mehrdad
authors.initials: M
authors.lastname: Arjomandi
authors.forename: Wenwu
authors.initials: W
authors.lastname: Zhai
authors.forename: Michael
authors.initials: M
authors.lastname: Kleinman
authors.forename: John
authors.initials: J
authors.lastname: Balmes
mesh_terms: D000328:Adult; D001249:Asthma; D004804:Eosinophils / Q000276:immunology / Q000378:metabolism; D005260:Female; D006801:Humans; D006967:Hypersensitivity / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D009585:Nitrogen Dioxide / Q000378:metabolism*; D011014:Pneumonia; D039981:Pyroglyphidae; D012137:Respiratory System / Q000276:immunology*; D011795:Surveys and Questionnaires
chemical_list: D009585:Nitrogen Dioxide