Abstract 955 Poster Session IV, Tuesday, 5/4 (poster 89)

Respiratory Syncytial Virus (RSV) is the most common respiratory pathogen in infants and young children worldwide. The pathogenesis of RSV disease, and specifically the role of inflammatory mediators, is not well defined. Recent studies have demonstrated the presence of pro-inflammatory cytokines in respiratory secretions of children infected with RSV, however, there is limited information on the systemic cytokine response in these patients. In this prospective, case-control, observational study, we enrolled 18 children (10 intubated and 8 non-intubated; age: range 0.75 - 23 mos; median 2 mos) admitted to Children's Medical Center, Dallas, with RSV brochiolitis/pneumonia. Thirteen children with no signs or symptoms of respiratory tract infection were evaluated as controls. Blood, nasopharyngeal (NP) and tracheal (TA) samples were obtained from all study children and analyzed for IL-6, IL-8, and RANTES concentrations by ELISA. The NP and TA samples were also analyzed for white blood cell counts, and quantitative RSV culture. Results: 1) IL-6, IL-8 and RANTES were present in serum samples from all patients with RSV infection (IL-6, range: 6-1,447 pg/mL; IL-8, 22-450 pg/mL; and RANTES 1,7507-148,000 pg/mL). 2) IL-6 (177-9,617 pg/mL), IL-8 (360-51,950 pg/mL), and RANTES (3.7-1,426 pg/mL) concentrations were also detected in NP and TA samples of all patients. 3) IL-6 and IL-8 concentrations were significantly greater in serum samples of children with RSV infection than in those obtained from controls (p <0.001), however, RANTES concentrations did not differ significantly among the two groups. 4) Serum RANTES concentrations declined significantly between day 1 and day 5 (p = 0.02). 5) When serum samples from intubated patients were compared to those from non-intubated patients, there was a trend for greater concentrations of IL-6 and IL-8 in samples obtained from the intubated patients, however, the difference was not statistically significant. 6) We did not observe any significant correlation between the respiratory and serum concentrations of these cytokines. Conclusions: Our results suggest that IL-6, IL-8, and RANTES play a role in the systemic inflammatory response induced by RSV in children. This may have implications for future therapeutic strategies aimed at immunomodulation of RSV disease.