Interleukin-13 and interleukin-5 in induced sputum of eosinophilic bronchitis: comparison with asthma.
OBJECTIVE
Experimental studies on asthma have indicated that interleukin (IL)-13 induces airway hyperreactivity (AHR). However, it remains unproven that IL-13 is responsible for AHR in asthmatic patients. Eosinophilic bronchitis (EB) shows normal airway responsiveness despite eosinophilic airway inflammation of severity similar to that of asthma. This study evaluated the role of IL-13 in asthma by comparing the sputum IL-5 and IL-13 levels in both groups.


METHODS
Comparisons between asthma and EB would clarify the role of IL-13 in AHR. IL-5 and IL-13 were assayed in the sputum and culture supernatants of peripheral blood mononuclear cells (PBMCs) from 22 asthmatic patients, 12 EB patients, and 11 healthy control subjects.


RESULTS
IL-13 levels were higher in the asthmatic patients than in the EB patients or healthy control subjects (p = 0.001). IL-5 levels were similar in the asthmatic patients and EB patients, who had significantly higher levels than those of healthy control subjects. Sputum IL-13, but not IL-5, is inversely correlated with the provocative concentration of a substance causing a 20% fall in FEV1 for methacholine in asthmatic patients (r = -0.502; p = 0.017). IL-13 production by PBMCs was significantly higher in asthmatic patients than in EB patients (p = 0.015), but the levels between EB patients and healthy control subjects was comparable.


CONCLUSIONS
The results of the present study indicate that IL-13 is related to AHR in asthmatic patients.
Park
Sung-Woo
SW
Asthma and AAllergy Research Group, Soonchunhyang University, Bucheon Hospital, 1174, Jung Dong, Wonmi Ku, Bucheon, Gyeonggi Do, 420-021, Korea.
Jangm
Hee Kyung
HK
An
Mi Hyoun
MH
Min
Ji Won
JW
Jang
An-Soo
AS
Lee
June-Hyuk
JH
Park
Choon-Sik
CS
D001249:Asthma / Q000276:immunology; D016535:Bronchial Hyperreactivity; D001991:Bronchitis / Q000276:immunology*; D004804:Eosinophils / Q000276:immunology; D006801:Humans; D018793:Interleukin-13 / Q000032:analysis*; D015848:Interleukin-5 / Q000032:analysis; D013183:Sputum / Q000276:immunology*
D018793:Interleukin-13; D015848:Interleukin-5