Lower number of plasmacytoid dendritic cells in peripheral blood of children with bronchiolitis following respiratory syncytial virus infection

OBJECTIVES Dendritic cells (DCs) are key mediators of allergic airway inflammation. Thus, it is important to understand the relationship between respiratory syncytial virus (RSV) infection and DCs, especially in children with RSV bronchiolitis. METHODS We collected peripheral blood from 71 children with RSV bronchiolitis at the time of admission and 28 children who were followed up 3 months following admission. Flow cytometry was performed to detect dendritic cell immunophenotypes. RESULTS Patients with RSV bronchiolitis exhibited significantly higher number of myeloid DCs and lower number of plasmacytoid DCs at the time of admission and 3 months following discharge, compared with healthy controls. These children had a significantly higher myeloid/plasmacytoid ratio 3 months after discharge compared with healthy controls. CONCLUSIONS Among children with RSV bronchiolitis, there is an imbalance in peripheral blood myeloid/plasmacytoid ratio. The low number of plasmacytoid DCs in peripheral blood indicates the development of bronchiolitis due to RSV infection.