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.