CD11c(+)B220(+)Gr-1(+) cells in mouse lymph nodes and spleen display characteristics of plasmacytoid dendritic cells

Human plasmacytoid dendritic cells (pDCs) are major producers of IFN alpha, are activated by CpG motifs, and are believed to enter lymph nodes (LNs) v ia L-selectin dependent extravasation across high endothelial venules. To i dentify a similar murine DC type, CD11c(+) cells in the LNs of L-selectin-d eficient and control BALB/c mice were compared, revealing a population of C D11c(+)CD11b(-) cells that is reduced 85% in the LNs of L-selectin-deficien t mice. These cells are Gr-1(+)B220(+)CD19(-), either CD4(+) or CD8(+), and localize within T cell zones of LNs. Freshly isolated CD11c(+)Gr-1(+) cell s express major histo compatibility complex class II at low levels, display a plasmacytoid morphology, and survive poorly in culture. Their survival i s increased and they develop a DC-like morphology in interleukin 3 and CpG. Like human pDCs, CD11c(+)Gr-1(+) cells stimulate T cell proliferation afte r activation with CpG and produce IFN alpha after stimulation with influenz a virus. These cells also display a strain-specific variation in frequency, being fivefold increased in the LNs of BA-LB/c relative to C57BL/6 mice. T hese CD11c(+)CD11b(-)B220(+)Gr-1(+) cells appear to be the murine equivalen t of human pDCs.