Human monocytes represent a competitive source of interferon-alpha in peripheral blood

Clin Immunol. 2008 May;127(2):252-64. doi: 10.1016/j.clim.2008.01.014. Epub 2008 Mar 14.


Interferon-alpha (IFN-alpha) has a critical role in antiviral immunity and plasmacytoid dendritic cells (pDCs) have been demonstrated as the principal IFN-alpha source after Toll-like receptor (TLR) 7 and 9 stimulation. Little is known about the contribution of pDC-independent IFN-alpha sources to total IFN-alpha production capacity of human peripheral blood. Using an array of pathogen associated molecular patterns (PAMPs), Poly(I:C)/Dotap represented the second strongest IFN-alpha stimulus in total PBMC. Poly(I:C)/Dotap induced three times more IFN-alpha, when compared to TLR7-stimulation (R848) and four times less, when compared to TLR9-stimulation. Dotap (mediator of cellular uptake) dramatically increased Poly(I:C)-induced IFN-alpha production. Sorting experiments and ELISpot assays revealed that monocytes and not myeloid DCs are the main IFN-alpha source after Poly(I:C)/Dotap stimulation. ELISpot analyses demonstrated the highest IFN-alpha spot numbers after Poly(I:C)/Dotap stimulation. Although pDCs produced highest IFN-alpha levels per cell, monocytes represent a competing IFN-alpha source in total PBMC due to their high frequency.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Fatty Acids, Monounsaturated / chemistry
  • Flow Cytometry
  • Fluorescent Dyes / chemistry
  • Humans
  • Imidazoles / immunology
  • Immunophenotyping / methods
  • Interferon-alpha / biosynthesis
  • Interferon-alpha / blood*
  • Interferon-alpha / immunology*
  • Lipopolysaccharide Receptors / immunology
  • Male
  • Monocytes / immunology*
  • Oligodeoxyribonucleotides / immunology
  • Poly I-C / immunology
  • Poly I-C / pharmacology
  • Quaternary Ammonium Compounds / chemistry
  • Statistics, Nonparametric
  • Toll-Like Receptor 7 / immunology


  • CpG ODN 2006
  • Fatty Acids, Monounsaturated
  • Fluorescent Dyes
  • Imidazoles
  • Interferon-alpha
  • Lipopolysaccharide Receptors
  • Oligodeoxyribonucleotides
  • Quaternary Ammonium Compounds
  • TLR7 protein, human
  • Toll-Like Receptor 7
  • 1,2-dioleoyloxy-3-(trimethylammonium)propane
  • Poly I-C
  • resiquimod