Levels of IL-32 in Serum, Induced Sputum Supernatant, and Bronchial Lavage Fluid of Patients with Chronic Obstructive Pulmonary Disease

Interleukin-32 (IL-32) is a newly described cytokine which is expected to have an important role in autoimmune disorders. It was shown that chronic obstructive pulmonary disease (COPD) has a component of autoimmunity, though the role of IL-32 in its pathogenesis is not known. The aim of this study was to estimate IL-32 concentrations in serum, induced sputum (IS) supernatant and bronchoalveolar lavage (BAL) fluid from patients with COPD, and to compare asthma patients with and healthy subjects. Outpatients with COPD (63.7 ± 8.4 years, n = 51), asthma (58.3 ± 12.4 years, n = 31), and healthy subjects (59.8 ± 8.2 years, n = 9) were studied. The levels of IL-32 in serum, BAL fluid, and IS supernatant samples were analyzed by ELISA. Concentrations of IL-32 were higher in all the studied materials from patients with COPD (BAL 22.46 ± 2.48 pg/ml, IS 19.66 ± 1.69 pg/ml, serum 26.77 ± 2.56 pg/ml) in comparison with patients with asthma (BAL 6.25 ± 1.08 pg/ml, IS 5.82 ± 1.15 pg/ml, serum 6.09 ± 1.16 pg/ml, p < 0.05 respectively) as well as healthy subjects (BAL 4.21 ± 1.13 pg/ml, IS 3.59 ± 0.66 pg/ml, serum 4.63 ± 1.03 pg/ml, p < 0.05 respectively). Moreover, the level of IL-32 was higher in COPD smokers than in COPD ex-smokers in investigated respiratory tissue compartments and serum, and correlated with smoking history. Increased level of IL-32 in serum, IS supernatant, and BAL fluid from patients with COPD in comparison with asthma patients and healthy subjects suggest that IL-32 may play an important role in the pathogenesis of COPD, which depends on the smoking history.