Lymphoid origin of intrinsically activated plasmacytoid dendritic cells in mice

Area of Science:

• Immunology
• Cell Biology
• Developmental Biology

Background:

• Plasmacytoid dendritic cells (pDCs) are crucial immune regulators.
• Conventional pDCs originate from common lymphoid progenitors (CLPs).
• The full diversity of pDC subsets and their developmental pathways remain incompletely understood.

Purpose of the Study:

• To identify and characterize novel pDC lineages in mice.
• To investigate the developmental origin and functional properties of a newly identified pDC subset.
• To compare the characteristics of this novel pDC subset with conventional pDCs and human transitional DCs.

Main Methods:

• Flow cytometry and cell sorting to isolate pDC subsets.
• Gene expression profiling (RNA sequencing) to analyze unique transcriptional signatures.
• In vitro functional assays to assess T cell proliferation.
• Analysis of cell surface marker expression (e.g., SIGLEC-H, PDCA1, AXL).

Main Results:

• A novel pDC lineage, termed 'B-pDCs', was identified, originating from CLPs and dependent on Bcl11a expression.
• B-pDCs exhibit a unique gene expression profile including B cell-associated genes, distinct from conventional pDCs.
• While expressing canonical pDC markers, B-pDCs lack IFN-α secretion but exhibit enhanced T cell proliferation upon TLR9 stimulation.
• Elevated AXL receptor expression in B-pDCs mirrors functional and transcriptional profiles of human AXL+ transitional DCs.

Conclusions:

• Murine B-pDCs represent a distinct CLP-derived dendritic cell lineage with specialized functions in T cell activation.
• This finding expands the known diversity of pDC populations in mice.
• B-pDCs offer a valuable model for studying human AXL+ transitional DCs and their role in immune responses.