In severe RSV bronchiolitis in infants, neutrophils can account for the majority of cells recovered from the airways, associated with increased neutrophil elastase (122–125) and IL-8 (94, 126), although others have reported a lower inflammatory cytokine response in infants with severe vs mild RSV bronchiolitis (127). This evidence concerns the gene CXCL8 and respiratory syncytial virus bronchiolitis.