Characteristics of asthmatics with detectable IL-32γ in induced sputum

Abstract Background Interleukin-32(IL-32)γ is a pro-inflammatory cytokine involved in the development and severity of chronic inflammatory diseases, but its role in asthma is unclear. Objective This study was conducted to evaluate the relationship of IL-32γ levels in sputum with the severity of asthma. Methods IL-32γ levels in the supernatant of induced sputum obtained from 89 patients with stable asthma were measured using a sandwich enzyme-linked immunosorbent assay (ELISA). The relationships between sputum IL-32γ levels and baseline forced expiratory volume in 1 s (FEV 1 % pred.), inflammatory cell profiles in sputum, and annual frequency of asthma exacerbation were determined. Results IL-32γ was detected in the sputum of 25 of 89 (28.1%) asthma patients, and the levels of sputum were negatively correlated with FEV 1 % pred. (ρ = −0.312, p = 0.003). The annual exacerbation rate was significantly higher in this group than in the IL-32-negative group (n = 64) (p = 0.03). Sputum IL-32γ levels correlated well with the annual exacerbation rate (ρ = 0.261, p = 0.014), but there were no differences in the inflammatory cell profiles in the induced sputum of IL-32-positive and IL-32-negative patients. Conclusion The level of IL-32γ in induced sputum may be associated with asthma severity and related with higher risk of asthma exacerbation.