Low birth weight contributed to increased serum IL-6 levels in infantile respiratory syncytial virus infection

BACKGROUND To evaluate the role of serum cytokines in the pathogenesis of respiratory syncytial virus (RSV) infection in infants with low birth weight (LBW). METHODS A prospective observational study was performed, and hospitalized children with lower respiratory tract infection (LRTI) were recruited. Three hundred fifty-eight patients < 1 year met the inclusion criteria: 116 patients had only RSV infection (RSV group); 242 patients had no RSV or other specific pathogen (non-RSV group). Serum interleukin-2 (IL-2), IL-4, IL-6, IL-10, tumor necrosis factor-α (TNF-α), and interferon-γ (IFN-γ) were detected through flow cytometry. RESULTS No significant differences in serum IL-2, 4, 6, 10, and IFN-γ levels were observed between the RSV and non-RSV groups. For RSV infected infants with or without wheezing, delivery mode had no obvious effect on the changes of serum cytokine levels. However, the level of IL-6 in the RSV-infected infants with LBW was significantly higher than that in infants with normal birth weight. CONCLUSIONS Serum IL-6 level was significantly increased in RSV infected infants with LBW. It is likely that the specific serum cytokine pattern will contribute to our understanding of the pathogenesis of RSV infections, especially in RSV-infected infants with LBW.