Type III IFNs are produced by and stimulate human plasmacytoid dendritic cells.

Plasmacytoid dendritic cells (pDC) are rare cells found in peripheral blood and lymphoid tissues. pDC are considered to be "professional" type I IFN-producing cells and produce 10- to 100-fold more IFN-α than other cell types in response to enveloped viruses or synthetic TLR7 and TLR9 agonists. In this study, purified pDC were found to express high levels of IFN-λ receptor mRNA, as well as cell-surface IFN-λ receptor.

Characterization of virus-responsive plasmacytoid dendritic cells in the rhesus macaque.

Plasmacytoid dendritic cells (PDC) are potent producers of alpha interferon (IFN-alpha) in response to enveloped viruses and provide a critical link between the innate and adaptive immune responses. Although the loss of peripheral blood PDC function and numbers has been linked to human immunodeficiency virus (HIV) progression in humans, a suitable animal model is needed to study the effects of immunodeficiency virus infection on PDC function. The rhesus macaque SIV model closely mimics human HIV infection, and recent studies have identified macaque PDC, potentially making the macaque a good model to study PDC regulation.

Regulation of IFN regulatory factor-7 and IFN-alpha production by enveloped virus and lipopolysaccharide in human plasmacytoid dendritic cells.

Human plasmacytoid dendritic cells (PDC) are a major source of IFN-alpha upon exposure to enveloped viruses and TLR-7 and TLR-9 ligands. Although IFN regulatory factor-7 (IRF-7) is known to play an essential role in virus-activated transcription of IFN-alpha genes, the molecular mechanisms of IFN-alpha production in human PDC remain poorly understood. We and others have recently reported high constitutive levels of IRF-7 expression in PDC as compared with other PBMC.

Virally stimulated plasmacytoid dendritic cells produce chemokines and induce migration of T and NK cells.

The natural interferon (IFN)-producing cell is now known to be identical to the plasmacytoid dendritic cell (PDC). These are Lin-, CD123+, CD11c-, and human leukocyte antigen-DR+ cells that secrete large amounts of IFN-alpha (1-2 IU/cell) when stimulated by enveloped viruses such as herpes simplex virus. In the current study, we have evaluated chemokine expression by virally stimulated PDC.