Immunoadjuvant effects of polyadenylic: Polyuridylic acids through TLR3 and TLR7

Takahiro Sugiyama, Katsuaki Hoshino, Masuyoshi Saito, Takahiro Yano, Izumi Sasaki, Chihiro Yamazaki, Shizuo Akira, Tsuneyasu Kaisho

Research output: Contribution to journalArticlepeer-review

49 Citations (Scopus)


Double-stranded RNA (dsRNA) is produced upon viral infection and can activate innate immunity. Polyinosinic:polycytidylic acids [poly(I:C)] is a synthetic mimetic of dsRNA and functions through an endosomal receptor, Toll-like receptor (TLR) 3 or cytosolic receptors. Another type of dsRNA, polyadenylic:polyuridylic acids [poly(A:U)], can also act as an immune adjuvant, but it remains unclear how it exhibits its adjuvant effects. Here, we have characterized the adjuvant effects of poly(A:U). Poly(A:U) could induce both IFN-α and IL-12p40 from murine bone marrow dendritic cells (DCs). Poly(A:U)-induced IFN-α production depended on a DC subset, plasmacytoid dendritic cell (pDC), and required TLR7. IL-12p40 was also produced by poly(A:U)-stimulated pDC in a TLR7-dependent manner. In addition to pDC, conventional dendritic cell (cDC) also produced IL-12p40 in response to poly(A:U). This IL-12p40 induction resulted from two cDC subsets, CD24high cDC and CD11bhigh cDC in a TLR3- and TLR7-dependent manner, respectively. In vivo injection of poly(A:U) with antigen led to clonal expansion of and IFN-γ production from antigen-specific CD8+ T cells. Consistent with the in vitro findings, TLR3 and TLR7 were required for the clonal T-cell expansion. Notably, TLR3, rather than TLR7, was critical for generating IFN-γ-producing CD8+ T cells. CD8+ T-cell responses induced by poly(A:U) were independent of type I IFN signaling. Our results demonstrate that poly(A:U) functions as an in vivo immunoadjuvant mainly through TLR3 and TLR7.

Original languageEnglish
Pages (from-to)1-9
Number of pages9
JournalInternational Immunology
Issue number1
Publication statusPublished - Jan 2008


  • Dendritic cell
  • Double-stranded RNA
  • Immune adjuvant
  • Toll-like receptor

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology


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