title: Effect of allergen avoidance at high altitude on direct and indirect bronchial hyperresponsiveness and markers of inflammation in children with allergic asthma.
abstract: BACKGROUND
  Improvement of allergic asthma is seen at high altitude partly because of low concentrations of allergen, especially house dust mite. To investigate the effect of a hypoallergenic environment (Davos, 1560 m) on airways inflammation, the changes in bronchial hyperresponsiveness measured with methacholine and adenosine 5'-monophosphate (AMP), blood eosinophils, eosinophil cationic protein (ECP), and serum IgE were studied.
  
  
  METHODS
  In 16 allergic asthmatic children tests were performed on admission and after one month. Medication was kept unchanged during the month of investigation and the patients performed peak expiratory flow (PEF) measurements twice daily.
  
  
  RESULTS
  After one month at high altitude a considerable improvement was seen in the provocative concentration of AMP causing a 20% fall in forced expiratory volume in one second (PC20 AMP), but not with methacholine. There was also a reduction in total blood eosinophils and ECP. No change in serum IgE was observed. Peak flow variability decreased.
  
  
  CONCLUSIONS
  After one month at high altitude a reduction in airways inflammation occurs. The results indicate that AMP responsiveness is a more accurate marker of disease activity in relation to inflammation in asthma than methacholine. The benefits of allergen avoidance at high altitude have important clinical implications for children with allergic asthma.
authors.affiliation: Dutch Asthmacentre Davos, Switerzland.
authors.forename: E
authors.initials: E
authors.lastname: van Velzen
authors.forename: J W
authors.initials: JW
authors.lastname: van den Bos
authors.forename: J A
authors.initials: JA
authors.lastname: Benckhuijsen
authors.forename: T
authors.initials: T
authors.lastname: van Essel
authors.forename: R
authors.initials: R
authors.lastname: de Bruijn
authors.forename: R
authors.initials: R
authors.lastname: Aalbers
mesh_terms: D000249:Adenosine Monophosphate; D000293:Adolescent; D000485:Allergens; D000531:Altitude; D001249:Asthma / Q000276:immunology / Q000503:physiopathology*; D001798:Blood Proteins / Q000378:metabolism; D016535:Bronchial Hyperreactivity / Q000175:diagnosis / Q000276:immunology / Q000628:therapy*; D002648:Child; D047091:Eosinophil Granule Proteins; D004804:Eosinophils / Q000473:pathology; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood; D007958:Leukocyte Count; D008297:Male; D016210:Methacholine Chloride; D012260:Ribonucleases
chemical_list: D000485:Allergens; D001798:Blood Proteins; D047091:Eosinophil Granule Proteins; D016210:Methacholine Chloride; D007073:Immunoglobulin E; D000249:Adenosine Monophosphate; D012260:Ribonucleases