Type III IFN-lambda mRNA expression in sputum of adult and school-aged asthmatics.
BACKGROUND
The increased susceptibility of asthmatics to rhinovirus infection has recently been related to deficient IFN-lambda 1 (IL-29) and IFN-lambda 2/3 (IL-28) production by bronchial epithelial cells and macrophages.


OBJECTIVE
Here, we studied IFN-lambda mRNA expression in the airways of stable asthmatics in comparison with healthy subjects and in relation to asthma symptoms, non-invasive parameters of airway inflammation and lung function parameters.


METHODS
Airway cells were obtained by sputum induction, in 14 healthy and 35 asthmatic adults and 12 asthmatic school-aged children. IFN-lambda was studied at the mRNA level by quantitative RT-PCR.


RESULTS
Asthmatic adults have increased sputum IL-28 mRNA but similar IL-29 mRNA expression in comparison with healthy subjects. In asthmatics, both sputum IL-28 and IL-29 mRNA expression correlate with the sputum CD3 gamma mRNA expression (reflecting infiltrated T cells). IL-28 (but not IL-29) mRNA levels correlate with the relative and absolute number of eosinophils present in the sputum sample. Sputum IL-29 mRNA (but not IL-28) correlates negatively with asthma symptoms in steroid-naive patients and is significantly higher in steroid-treated than in steroid-naive patients. Finally, both IL-28 and IL-29 mRNA levels are higher in asthmatic children than in asthmatic adults.


CONCLUSIONS
Our results show that asthmatic subjects have substantial type III IFN-lambda mRNA levels in the airways. Our data furthermore suggest that IL-29 could have an immunoprotective role in the lower airways.
Bullens
Dominique M A
DM
Clinical Immunology, Department of Experimental Medicine, Katholieke Universiteit Leuven (KULeuven), Leuven, Belgium. Dominique.Bullens@med.kuleuven.be
Decraene
A
A
Dilissen
E
E
Meyts
I
I
De Boeck
K
K
Dupont
L J
LJ
Ceuppens
J L
JL
D000328:Adult; D000368:Aged; D018927:Anti-Asthmatic Agents / Q000627:therapeutic use; D001249:Asthma / Q000188:drug therapy / Q000276:immunology / Q000378:metabolism*; D001507:Beclomethasone / Q000627:therapeutic use; D002648:Child; D005260:Female; D006801:Humans; D007372:Interferons; D007378:Interleukins / Q000096:biosynthesis* / Q000235:genetics; D008297:Male; D008875:Middle Aged; D012333:RNA, Messenger / Q000096:biosynthesis*; D013183:Sputum / Q000166:cytology / Q000378:metabolism*; D055815:Young Adult; D000095022:Interferon Lambda
D018927:Anti-Asthmatic Agents; D001507:Beclomethasone; D007372:Interferons; D007378:Interleukins; D012333:RNA, Messenger; C000624353:interferon-lambda, human; D000095022:Interferon Lambda