Dendritic cell type 3 arises from Ly6C⁺ monocyte-dendritic cell progenitors

Area of Science:

• Immunology
• Cell Biology
• Developmental Biology

Background:

• Conventional dendritic cells (cDCs) are vital antigen-presenting cells regulating adaptive immunity.
• The precise developmental origins and distinct lineages of cDC subsets, particularly DC2 and human DC3, remain unclear due to overlapping phenotypes with monocytes.

Purpose of the Study:

• To differentiate dendritic cell (DC) lineages from monocytes using molecular markers.
• To elucidate the distinct developmental pathways of DC3 and DC2 subsets.

Main Methods:

• Utilized LEGENDScreen for comprehensive profiling of DC versus monocyte lineages.
• Employed fate mapping models, single-cell RNA sequencing, and adoptive transfer techniques.
• Analyzed key surface markers including FLT3, CD45RB, CD16/32, CD172a, Ly6C, and CD11c.

Main Results:

• Identified sustained expression of FLT3 and CD45RB as reliable markers to distinguish DCs and their precursors from monocytes.
• Defined a distinct murine CD16/32+CD172a+ DC3 lineage originating from monocyte-DC progenitors (MDPs) via Lyz2+Ly6C+CD11c- pro-DC3s.
• Established that DC2s develop from common DC progenitors (CDPs) through CD7+Ly6C+CD11c+ pre-DC2s, confirming DC3 and DC2 as separate lineages.
• Confirmed the existence of analogous DC subsets, developmental stages, and lineages in humans.

Conclusions:

• DC3 represents a distinct dendritic cell lineage phenotypically related to, but developmentally separate from, monocytes and DC2s.
• The identified markers and developmental pathways provide a clearer understanding of immune cell differentiation and function.