ABSTRACT
Dendritic cells (DCs) are professional antigen-presenting cells linking innate and adaptive immunity. DCs recognize and are activated by nucleic acid adjuvants through the Toll-like receptor (TLRs) or non-TLR systems. Compared with lipid or protein adjuvants, nucleic acid adjuvants are distinguished by the ability to induce type I interferon (IFN), especially IFN-α. DCs are heterogeneous and respond to nucleic acids in a subset-specific manner. Plasmacytoid DCs (PDCs) constitute a unique DC subset specialized for nucleic acid sensing through TLRs that can secrete vast amounts of type I IFNs in response to TLR signaling. We review DC responses to nucleic acid adjuvants, focusing on PDCs. Clarifying the molecular mechanisms by which TLR-stimulated PDCs produce type I IFN should contribute to the establishment of effective therapeutic strategies to regulate antiviral immunity, autoimmunity, and allergies.
