Objective Respiratory syncytial virus ( RSV) is a primary cause of lower respiratory tract infections in children, and is also the cause for the development of asthma primarily in infants. However,the immunological mechanisms by which RSV enhances allergic sensitization and asthma remain unclear. The aimof this study was to examine the influence of RSV-infected airway epithelial cells on the activation and functions of rat myeloid dendritic cells ( mDCs) . Methods Rat airway epithelial cells ( RAECs) were infected by RSV. Then RSV-infected RAECs were co-cultured with rat mDCs, and the expression of cytokine and maturation markers on mDCs were examined by real time PCR and flow cytometry. To confirm this functional mDC maturation, allergenic mixed lymphocyte reaction ( MLR) were performed. Results Wefound that functional maturation of mDCs was induced by RSV-treated RAECs, as shown by their enhanced levels of OX40L and thymus- and activation-regulated chemokine ( TARC) mRNAs, which increased the expressions of major histocompatibility complex II ( MHCII) and CD86 costimulatorymolecules and promotedT-cell proliferation in mixed lymphocyte reactions. Conclusion Our results suggest that RSV-infected epithelial cells promote the maturation of mDCs that might support Th2 cell polarization and contribute to the pathogenesis of asthma.