Interleukin-18 in induced sputum: Association with lung function in chronic obstructive pulmonary disease

SummaryBackgroundIt has been shown that interleukin (IL)-18 levels in induced sputum are reduced in asthmatic and healthy smokers. However, in chronic obstructive pulmonary disease (COPD) patients, recent data show an overproduction in the lungs and increased serum levels of IL-18, suggesting that IL-18 may be involved in the pathogenesis of COPD.MethodIn order to assess the relation of IL-18 with pulmonary function and airway inflammation in COPD, IL-18, tumour necrosis factor-α, and IL-8 levels were measured by ELISA in sputum supernatants obtained from patients with bronchitis type COPD (n=28), and healthy subjects (18 smokers and 17 non-smokers). Cellular localization of IL-18 was assessed by immunocytochemistry.ResultsThe levels of IL-18 were significantly higher in sputum supernatants of COPD patients compared to healthy smokers and non-smokers (p