Correlation between respiratory function and airway inflammation in asthma.
BACKGROUND
Eosinophilic airway inflammation is thought to be associated with airflow limitation and airway hyperresponsiveness.


METHODS
Spirometry, peak expiratory flow (PEF) measurement, histamine challenge test, and sputum induction with hypertonic saline inhalation were performed in 70 asymptomatic patients with asthma who were treated with bronchodilators or an inhaled corticosteroid (beclomethasone dipropionate, 400-800 microg/day) or both for more than 2 months. The relationships between the sputum eosinophils, respiratory function, and airway responsiveness to histamine were investigated.


RESULTS
Induced sputum was obtained from 53 patients. Although significant correlations between sputum eosinophils and forced expiratory volume in 1 s/forced vital capacity x 100% (FEV1%) or maximum expiratory flow at 25% of the forced vital capacity (V25) divided by height (V25/Ht) were observed, no significant correlations were found between sputum eosinophils and percent predicted PEF (%PEF) or airway responsiveness to histamine. Furthermore, airway responsiveness to histamine was not correlated with FEV1%, V25/Ht or %PEF.


CONCLUSIONS
Single-point measurements of FEV1% and V25/Ht but not PEF or airway responsiveness to histamine correlate with the degree of airway inflammation evaluated indirectly with induced sputum.
Hashimoto
T
T
First Department of Internal Medicine, Showa University, Tokyo, Japan.
Minoguchi
K
K
Kohno
Y
Y
Wada
K
K
Ueno
K
K
Kobayashi
H
H
Miyamoto
M
M
Adachi
M
M
D000328:Adult; D001249:Asthma / Q000276:immunology / Q000503:physiopathology*; D004804:Eosinophils / Q000276:immunology*; D005260:Female; D006632:Histamine / Q000276:immunology; D006801:Humans; D007249:Inflammation / Q000276:immunology / Q000503:physiopathology*; D008297:Male; D012119:Respiration; D012137:Respiratory System / Q000276:immunology / Q000503:physiopathology*; D013183:Sputum
D006632:Histamine