Plasmacytoid dendritic cell precursors/type I interferon-producing cells sense viral infection by Toll-like receptor (TLR) 7 and TLR9

Springer Semin Immunopathol. 2005 Jan;26(3):221-9. doi: 10.1007/s00281-004-0180-4. Epub 2004 Nov 13.


Plasmacytoid dendritic cell (pDC) precursors, also called type I IFN (alpha/beta/omega)-producing cells (IPCs), are the key effectors in the innate immune system because of their extraordinary capacity to produce type I IFNs against microbial infection, particularly viral infection. In contrast to myeloid DCs, human pDC/IPCs selectively express Toll-like receptor (TLR) 7 and TLR9 within the endosomal compartment. These receptors are specifically designed to recognize the nucleoside-based products derived from RNA viruses and DNA viruses. Therefore, this expression profile potentially enables pDC/IPCs to sense a variety of viruses. Stimulation of TLR7 or TLR9 leads to type I IFN responses through the MyD88 pathway. Thus, pDC/IPCs may play a central role in host defense against viral infection through the TLR7 and TLR9 system.

Publication types

  • Review

MeSH terms

  • Animals
  • Cytokines / biosynthesis
  • Dendritic Cells / immunology*
  • Humans
  • Immunity, Innate
  • Interferon Type I / biosynthesis
  • Membrane Glycoproteins / immunology*
  • Mice
  • Models, Immunological
  • Receptors, Cell Surface / immunology*
  • Stem Cells / immunology
  • Toll-Like Receptor 7
  • Toll-Like Receptor 9
  • Toll-Like Receptors
  • Virus Diseases / immunology*


  • Cytokines
  • Interferon Type I
  • Membrane Glycoproteins
  • Receptors, Cell Surface
  • TLR7 protein, human
  • TLR9 protein, human
  • Toll-Like Receptor 7
  • Toll-Like Receptor 9
  • Toll-Like Receptors