title: Clinical features and airway inflammation in mild asthma versus asymptomatic airway hyperresponsiveness.
abstract: BACKGROUND
  We still do not know why some subjects with airway hyperresponsiveness (AHR) experience no respiratory symptoms.
  
  
  OBJECTIVE
  Our aim was to compare pulmonary function, perception of bronchoconstriction, and airway inflammation in atopic subjects with mild recently diagnosed (<5 years, n=30) or longer-standing (5 years or more, n=30) symptomatic asthma in comparison with atopic subjects with asymptomatic AHR (n=27).
  
  
  METHODS
  All subjects had measurements of expiratory flows, PC(20) methacholine, perception of breathlessness and induced sputum cell differential, eosinophil cationic protein and alpha(2)-macroglobulin levels.
  
  
  RESULTS
  Compared with the other groups, PC(20) was significantly lower in longer-standing asthma and perception score for breathlessness at 20% fall in FEV(1) was lower in asymptomatic subjects. Markers of airway inflammation were similar in all groups. There were no significant correlations between sputum eosinophils, alpha(2)-macroglobulin and/or eosinophil cationic protein levels and FEV(1), FVC or PC(20) in either group.
  
  
  CONCLUSIONS
  Subjects with mild asthma or asymptomatic AHR are similar in regard to induced sputum markers of airway inflammation. Although perception of bronchoconstriction was slightly lower in asymptomatic subjects, additional factors are probably involved to explain why they report no respiratory symptoms. Further studies are needed to determine why these last are asymptomatic.
authors.affiliation: Unité de Recherche en Pneumologie de l'Hôpital Laval, Institut Universitaire de Cardiologie et de Pneumologie de l'Université Laval, 2725 Ch. Ste-Foy, Québec, Canada. lpboulet@med.ulaval.ca
authors.forename: Louis-Philippe
authors.initials: LP
authors.lastname: Boulet
authors.forename: Philippe
authors.initials: P
authors.lastname: Prince
authors.forename: Hélène
authors.initials: H
authors.lastname: Turcotte
authors.forename: Catherine
authors.initials: C
authors.lastname: Lemière
authors.forename: Ronald
authors.initials: R
authors.lastname: Olivenstein
authors.forename: Catherine
authors.initials: C
authors.lastname: Laprise
authors.forename: Pierre
authors.initials: P
authors.lastname: Larivée
authors.forename: Paul
authors.initials: P
authors.lastname: Bégin
authors.forename: Michel
authors.initials: M
authors.lastname: Laviolette
mesh_terms: D000293:Adolescent; D000328:Adult; D001249:Asthma / Q000473:pathology* / Q000503:physiopathology; D016535:Bronchial Hyperreactivity / Q000473:pathology* / Q000503:physiopathology; D001985:Bronchial Provocation Tests; D001991:Bronchitis / Q000473:pathology*; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D013183:Sputum / Q000166:cytology; D014797:Vital Capacity / Q000502:physiology