Cells in Mouse Lymph Nodes and Spleen Display Characteristics of Plasmacytoid Dendritic Cells

Human plasmacytoid dendritic cells (pDCs) are major producers of IFN , are activated by CpG motifs, and are believed to enter lymph nodes (LNs) via L-selectin dependent extravasation across high endothelial venules. To identify a similar murine DC type, CD11c cells in the LNs of L-selectin–deficient and control BALB/c mice were compared, revealing a population of CD11c CD11b cells that is reduced 85% in the LNs of L-selectin–deficient 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 cells express major histocompatibility complex class II at low levels, display a plasmacytoid morphology, and survive poorly in culture. Their survival is increased and they develop a DC-like morphology in interleukin 3 and CpG. Like human pDCs, CD11c Gr-1 cells stimulate T cell proliferation after activation with CpG and produce IFN after stimulation with influenza virus. These cells also display a strain-specific variation in frequency, being fivefold increased in the LNs of BALB/c relative to C57BL/6 mice. These CD11c CD11b B220 Gr-1 cells appear to be the murine equivalent of human pDCs.