Leucocyte populations in respiratory syncytial virus-induced bronchiolitis.

Objectives: To enumerate the cellular composition of the airways in infants with acute bronchiolitis.
Methodology: Cells were obtained by airway lavage from the upper and lower airway and the peripheral blood of infants with respiratory syncytial virus (RSV)+ bronchiolitis, RSV- bronchiolitis and age-matched controls.
Results: Neutrophils are the predominant cells present in the upper and lower airway. Neutrophils are present at a higher number/unit volume in the airway than in the peripheral blood.
Conclusions: Neutrophils, being the dominant cellular infiltrate into the airway, are likely to contribute to the pathophysiology of bronchiolitis. Therapies targeted at limiting neutrophil influx or neutrophil-mediated damage in the airway may have a therapeutic role.