Nonplasmacytoid, High IFN-α-Producing, Bone Marrow Dendritic Cells

Plasmacytoid dendritic cells (pDC) are the producers of type I IFNs in response to TLR9 ligands. However, we have found that when bone marrow is depleted of pDC, the IFN-alpha produced in response to TLR9 ligands is not fully removed. We assign the source of this non-pDC IFN-alpha as a newly described DC type. It displays the high IFN-alpha producing activity of pDC but to a more limited range of viruses. Unlike pDC, the novel DC display high T cell stimulation capacity. Moreover, unlike mouse pDC, they are matured with GM-CSF and are less prone to apoptosis upon activation stimuli, including viruses. We propose that these DC constitute a novel bone marrow inflammatory DC type, ideally geared to linking innate and adaptive immune responses in bone marrow via their potent IFN-alpha production and high T cell stimulatory capacity. The Journal of Immunology, 2012, 188: 3774-3783.