Maturation, activation, and protection of dendritic cells induced by double-stranded RNA

The initiation of an immune response is critically dependent on the activat ion of dendritic cells (DCs). This process is triggered by surface receptor s specific for inflammatory cytokines or for conserved patterns characteris tic of infectious agents. Here we show that human DCs are activated by infl uenza virus infection and by double-stranded (ds)RNA. This activation resul ts not only in increased antigen presentation and T cell stimulatory capaci ty, but also in resistance to the cytopathic effect of the virus, mediated by the production of type I interferon, and upregulation of MxA. Because ds RNA stimulates both maturation and resistance, DCs can serve as altruistic antigen-presenting cells capable of sustaining viral antigen production whi le acquiring the capacity to trigger naive T cells and drive polarized T he lper cell type 1 responses.