Concentrations of IL-15, IL-18, IFN-γ and activity of CD4+, CD8+ and NK cells at admission in children with viral bronchiolitis

: The pathogenesis of viral bronchiolitis is poorly understood. The aim of this study was to analyze interleukin (IL)-15, IL-18 and interferon (IFN)-γ concentrations and the activity of NK cells and CD4+ and CD8+ lymphocytes in 23 children not older than 30 months of age with acute viral bronchiolitis using blood samples drawn within the first 24 h of their hospital admission, in comparison to a healthy group. In children with bronchiolitis, the mean concentrations of IL-15, IL-18 and IFN-γ were 9.39±11.55, 884.03±645.44 and 17.92±27.14 pg/ml, respectively, and were significantly higher than those in the control group [2.34±0.61 pg/ml (p<0.05), 248.69±98.73 pg/ml (p<0.001) and 2.75±1.72 pg/ml (p<0.005), respectively]. In the bronchiolitis group, mean z-scores were -1.15±1.9 for CD4+ cells and -0.9±1.23 for CD8+ cells; these scores were significantly lower than those of the general Polish population (p<0.001 and <0.01, respectively). However, the mean z-score of the ratio of CD4+/CD8+ and the NK cell count in children with bronchiolitis did not differ significantly from those of the controls. In conclusion, cytokines such as IL-15, IL-18 and IFN-γ play a role in the pathogenesis of bronchiolitis in children.