Airway IFN-γ Production During RSV Bronchiolitis is Associated with Eosinophilic Inflammation

This study was designed to investigate the possible role of IFN-gamma in eosinophil degranulation that occurs during respiratory syncytial virus (RSV) bronchiolitis. Sixty-seven infants, 2-24 months old and hospitalized with their first episode of acute RSV bronchiolitis, were selected for this study. Eosinophil-active cytokine and chemokine profiles in nasal lavage supernatants taken within the first 48 h of admission were determined by a multiplex bead array system (Luminex). Comparisons were made with control (Control group) subjects (n = 20). Nasal IFN-gamma levels were significantly higher (P < 0.0001) in RSV bronchiolitis (median = 4.4 pg/ml) infants compared to controls (0.0 pg/ml). IFN-gamma levels correlated significantly with the levels of nasal eotaxin (r = 0.566, P < 0.0001), RANTES (r = 0.627, P < 0.0001), GM-CSF (r = 0.849, P < 0.0001), and EDN (r = 0.693, P < 0.001). Nasal interleukin (IL)-4, IL-5, and IL-13 were below sensitivity levels in most RSV bronchiolitis and control subjects. These results suggest that IFN-gamma may play an important role in eosinophilic inflammation in RSV bronchiolitis.