Clinical features and airway inflammation in mild asthma versus asymptomatic airway hyperresponsiveness.
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.
Boulet
Louis-Philippe
LP
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
Prince
Philippe
P
Turcotte
Hélène
H
Lemière
Catherine
C
Olivenstein
Ronald
R
Laprise
Catherine
C
Larivée
Pierre
P
Bégin
Paul
P
Laviolette
Michel
M
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