Plasmacytoid dendritic cells develop from Ly6D+ lymphoid progenitors distinct from the myeloid lineage.

Dendritic cells (DC) are currently classified as conventional DCs (cDCs) and plasmacytoid DCs (pDCs). Through a combination of single-cell transcriptomic analysis, mass cytometry, in vivo fate mapping and in vitro clonal assays, here we show that, at the single-cell level, the priming of mouse hematopoietic progenitor cells toward the pDC lineage occurs at the common lymphoid progenitor stage, indicative of early divergence of the pDC and cDC lineages. We found the transcriptional signature of a pDC precursor stage, defined here, in the IL-7Rα+ common lymphoid progenitor population and identified Ly6D, IL-7Rα, CD81 and CD2 as key markers of pDC differentiation, which distinguish pDC precursors from cDC precursors. In conclusion, pDCs developed in the bone marrow from a Ly6DhiCD2hi lymphoid progenitor cell and differentiated independently of the myeloid cDC lineage.

Kupffer Cell Characterization by Mass Cytometry.

Kupffer cells are the liver-resident macrophages lining the sinusoids and are mostly known for their role of scavengers, as crucial keepers of organ integrity. But due to the many fundamental functions of the liver notably linked to detoxication, metabolism, protein synthesis, or immunology, Kupffer cells are exposed to a dynamic environment and constantly adapt themselves by modulating their gene and protein expressions. In this context, the characterization of these cells at steady-state and upon challenges may be limited by the classical microscopy or flow cytometry which allow for the use of only few selected markers. On the other end, transcriptomic approach, although being very powerful, can be costly and time-consuming. So mass cytometry offers a good compromise, allowing for the monitoring of a representative set of markers (up to 40) in a simple experiment. Herein, we describe a straightforward experimental and analysis workflow for Kupffer cell characterization by mass cytometry.