DC regulation of T cell responses in the lungs

Our studies have shown that influenza infections trigger a rapid but transient migration of mature rDC from the lungs to the lymph nodes. This halt in rDC migration results in a suppression of pulmonary T cell responses to subsequent infections and therefore may contribute to the high preponderance of secondary bacterial pneumonias that occur following respiratory virus infections. However the retention of the dendritic cells in the lungs also importantly allows local peripheral interactions of the dendritic cells with effector T cells - therein boosting pulmonary CD8 T cell responses and allowing viral clearance and recovery from infection. Specifically our studies have demonstrated that during this novel DC: T cell interaction that the DCs provide survival signals to the T cells via presentation of viral peptides in MHC class I molecules and through IL-15 transpresentation.