Although Respiratory syncytial virus (RSV)
bronchiolitis is the most important cause of hospital admission for infants during the winter season, the pathogenesis is largely unknown.
Interleukin-17 (IL-17) concentrations were studied in nasopharyngeal aspirates from 21 non-ventilated and 17 ventilated infants admitted to hospital with RSV
bronchiolitis at time of admission and discharge from the hospital. On admission, nasopharyngeal concentrations of most
cytokines and
chemokines were lower in non-ventilated infants than in ventilated infants, reaching statistical significance for Eotaxin, IL-1α, and
IL-6. During course of
disease, nasopharyngeal concentrations of most
cytokines and
chemokines decreased, reaching statistical significance for
IL-6 and IP-10. However, nasopharyngeal
IL-17 concentrations were higher at discharge than at admission in children with non-ventilated RSV disease (209-101 pg/ml, P = 0.008), a response pattern not observed in ventilated RSV patients nor for other
cytokines or
chemokines. It is speculated that local
IL-17 production may be involved during
convalescence from RSV
bronchiolitis in non-ventilated patients by facilitating innate and adaptive
antiviral immune responses. The role of
IL-17 in the pathogenesis of RSV
bronchiolitis is to be explored further.