ISSN:
1365-2222
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Medicine
Notes:
Background IL-18 is a cytokine which is known to have an important role in the development of a Th1 lymphocyte response. As such, it may have a regulatory role in asthma by modifying Th2 lymphocyte responses. Cigarette smoking may amplify the airway inflammation associated with asthma.Objective This study investigated if IL-18 could be detected in induced sputum from asthmatics and normal subjects and if smoking altered IL-18 levels.Methods Induced sputum was obtained from asthmatic (31 smokers, 35 non-smokers) and normal (20 smokers, 20 non-smokers) subjects. All smokers had a smoking history of 〈inlineGraphic alt="geqslant R: gt-or-equal, slanted" extraInfo="nonStandardEntity" href="urn:x-wiley:09547894:CEA1973:ges" location="ges.gif"/〉15 pack years. IL-18 levels in sputum supernatant were measured by ELISA. IL-18 mRNA expression and cellular localization were assessed by quantitative PCR and immunocytochemistry, respectively.Results Smoking was associated with a significant reduction in IL-18 levels (median (interquartile range) – smokers 20 (0–102) pg/mL vs. non-smokers 358 (50–876) pg/mL, P〈0.001). This was more pronounced in asthmatics (smokers, 47 (40–64) pg/mL vs. non-smokers, 530 (30–1484) pg/mL; P〈0.001) than in normal subjects (smokers, 25 (0–78) pg/mL vs. non-smokers, 247 (50–656) pg/mL; P〈0.01). Within each of the smoking and non-smoking groups there was no significant difference in IL-18 levels between asthmatic and normal subjects. There was no correlation between sputum IL-18 levels and any specific cell type in the sputum samples nor serum IgE levels. IL-18 mRNA expression was reduced in asthmatic smokers compared with non-smokers. IL-18 production was localized to sputum macrophages by immunocytochemistry.Conclusions IL-18 is detectable in induced sputum samples from both asthmatic and normal subjects. Cigarette smoking significantly reduces sputum IL-18 levels. This effect is more pronounced in asthmatics than in normal subjects.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1365-2222.2004.01973.x
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