Elevated cytokine concentrations in the nasopharyngeal and tracheal secretions of children with respiratory syncytial virus disease

Background. Respiratory syncytial virus (RSV) is the most common cause of l ower respiratory tract disease in infants. The role of inflammatory mediato rs in the pathogenesis of RSV disease is not well-understood. The present s tudy was de signed (1) to determine whether RANTES (regulated on activation , normal T cell expressed and presumably secreted), macrophage-inflammatory protein-1-alpha (MIP-l-alpha), interleukin (IL)-6, IL-8 and IL-10 can be d etected in respiratory secretions of children with RSV infection and (2) to assess whether the concentrations of these cytokines in respiratory secret ions correlate with white blood cell (WBC) counts and RSV concentrations an d with disease severity. Methods. During the 1996 to 1997 RSV season, we studied prospectively 14 in tubated and 14 nonintubated children hospitalized with RSV disease. Nasal w ash (NW) and tracheal aspirate (TA) samples were obtained from intubated pa tients on Hospital Days 1, 3 and 5, NW samples were obtained from nonintuba ted patients on hospital days 1 and 3, Seven healthy children undergoing el ective surgery served as controls, All samples were analyzed for: (1) WBC a nd differential counts; (2) concentrations of RANTES, MIP-l-alpha, IL-6, IL -8 and IL-10; and (3) quantitative RSV cultures, except in control patients . Results. RANTES, MIP-1-alpha, IL-6, IL-8 and IL-IO were detected in NW and TA samples from all children with RSV infection. The concentrations of thes e cytokines in samples obtained from children with RSV infection were signi ficantly greater than those in samples obtained from control children. NW W BC counts significantly correlated with NW RANTES, IL,-6, IL,-8 and IL-10 c oncentrations, whereas TA WBC counts significantly correlated with TA IL-6, IL-8, IL-10 and MIP I alpha concentrations. NW RSV concentrations correlat ed with NW WBC counts and with NW cytokine concentrations. Among children w ith RSV infection nonintubated patients had greater NW WBC counts and NW RA NTES concentrations than intubated patients. TA RANTES, IL-8 and IL-10 conc entrations inversely correlated with clinical markers of RSV disease severi ty. Conclusion. The presence of cytokines in NW and TA samples of children with RSV infection suggests that they have a role in mediating the respiratory tract inflammation induced by RSV, These observations could have implicatio ns for designing new therapeutic strategies directed at immunomodulation of RSV disease.