Plasmacytoid dendritic cell

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Plasmacytoid dendritic cells (pDCs) are innate immune cells that circulate in the blood and are found in peripheral lymphoid organs. They develop from bone marrow hematopoietic stem cells and constitute < 0.4% of peripheral blood mononuclear cells (PBMC).[1]

In humans they exhibit plasma cell morphology and express CD4, HLA-DR, CD123, blood-derived dendritic cell antigen-2 (BDCA-2), Toll-like receptor (TLR) 7 and TLR9 within endosomal compartments, but do not express high levels of CD11c or CD14, which distinguishes them from conventional dendritic cells or monocytes, respectively. Mouse pDC express CD11c, B220, BST-2/Tetherin (mPDCA) and Siglec-H and are negative for CD11b.

As components of the innate immune system, these cells express intracellular Toll-like receptors 7 and 9 which detect ssRNA and unmethylated CpG DNA sequences, respectively.[2] Upon stimulation and subsequent activation, these cells produce large amounts (up to 1,000 times more than other cell type) of type I interferon (mainly IFN-α (alpha) and IFN-β (beta)), which are critical pleiotropic anti-viral compounds mediating a wide range of effects.

The number of circulating pDCs are found to be decreased during chronic HIV infection as well as HCV infection.


  1. ^ Tversky JR, Le TV, Bieneman AP, Chichester KL, Hamilton RG, Schroeder JT (May 2008). "Human blood dendritic cells from allergic subjects have impaired capacity to produce interferon-alpha via Toll-like receptor 9". Clin. Exp. Allergy. 38 (5): 781–8. PMC 2707903Freely accessible. PMID 18318750. doi:10.1111/j.1365-2222.2008.02954.x. 
  2. ^ Gill MA, Bajwa G, George TA, et al. (June 2010). "Counterregulation between the FcepsilonRI pathway and antiviral responses in human plasmacytoid dendritic cells". J. Immunol. 184 (11): 5999–6006. PMID 20410486. doi:10.4049/jimmunol.0901194.