Sputum eosinophil counts and eosinophil cationic protein levels in cough-variant asthma and in classic asthma, and their relationships to airway hypersensitivity or maximal airway response to methacholine.
BACKGROUND
The aims of this study were to compare the degree of airway inflammation in cough-variant asthma (CVA) with that in classic asthma (CA), and to examine the relationship between airway inflammation and airway hypersensitivity or maximal airway response to methacholine in both conditions.


METHODS
Sputum was induced in 41 CVA patients, in 41 methacholine PC(20)-matched CA patients, and in 20 healthy children. The sputum samples were analyzed for total and differential cell counts, and for eosinophilic cationic protein (ECP). A high-dose methacholine challenge test was performed in CVA and CA patients to determine PC(20) and maximal airway response.


RESULTS
Sputum eosinophil percentages and ECP levels were significantly elevated in CVA and CA vs the control, but no significant differences were found between the two asthma groups. In the two asthma groups, neither sputum parameters correlated significantly with methacholine PC(20). However, the absence of a maximal response plateau or its higher level, when present, was associated with increased eosinophil percentages and ECP levels in the CVA group.


CONCLUSIONS
The degree of eosinophilic inflammation may not be causally related to differences in presented asthma manifestations. The identification of a maximal response plateau and the level of this plateau in patients with CVA may provide information pertinent to airway eosinophilic inflammation.
Yoo
Y
Y
Department of Pediatrics and Clinical Research Institute, Seoul National University Hospital, Seoul, Korea.
Koh
Y Y
YY
Kang
H
H
Yu
J
J
Nah
K M
KM
Kim
C K
CK
D000293:Adolescent; D001249:Asthma / Q000150:complications / Q000276:immunology*; D016535:Bronchial Hyperreactivity / Q000139:chemically induced / Q000276:immunology*; D001985:Bronchial Provocation Tests; D016085:Bronchoconstrictor Agents / Q000008:administration & dosage / Q000009:adverse effects; D002648:Child; D003371:Cough / Q000276:immunology; D004305:Dose-Response Relationship, Drug; D047150:Eosinophil Cationic Protein / Q000032:analysis / Q000276:immunology*; D004804:Eosinophils / Q000276:immunology*; D005260:Female; D005541:Forced Expiratory Volume / Q000187:drug effects; D006801:Humans; D007958:Leukocyte Count; D008297:Male; D016210:Methacholine Chloride / Q000008:administration & dosage / Q000009:adverse effects; D013183:Sputum / Q000276:immunology*
D016085:Bronchoconstrictor Agents; D016210:Methacholine Chloride; D047150:Eosinophil Cationic Protein