Subsets of CD1c+ DCs: Dendritic Cell Versus Monocyte Lineage.

Lukas Heger,I Jolanda M De Vries,Venetia Bigley,Loems Ziegler-Heitbrock,Marc Dalod,Thomas P Hofer,Diana Dudziak

doi:10.3389/fimmu.2020.559166

Abstract

Currently three bona fide dendritic cell (DC) types are distinguished in human blood. Herein we focus on type 2 DCs (DC2s) and compare the three defining markers CD1c, CD172, and CD301. When using CD1c to define DC2s, a CD14+ and a CD14− subset can be detected. The CD14+ subset shares features with monocytes, and this includes substantially higher expression levels for CD64, CD115, CD163, and S100A8/9. We review the current knowledge of these CD1c+CD14+ cells as compared to the CD1c+CD14− cells with respect to phenotype, function, transcriptomics, and ontogeny. Here, we discuss informative mutations, which suggest that two populations have different developmental requirements. In addition, we cover subsets of CD11c+CD8− DC2s in the mouse, where CLEC12A+ESAMlow cells, as compared to the CLEC12A−ESAMhigh subset, also express higher levels of monocyte-associated markers CD14, CD3, and CD115. Finally, we summarize, for both man and mouse, the data on lower antigen presentation and higher cytokine production in the monocyte-marker expressing DC2 subset, which demonstrate that the DC2 subsets are also functionally distinct.

Highlights

In human blood, cells with dendritic cell (DC) properties have been classified as plasmacytoid DCs, as CD141+ DCs and as CD1c+ DCs [1,2,3]
In order to appropriately address the question of lineage assignment of the subsets of CD1c+ DCs, approaches using a broad panel of different monocytes, macrophages, and dendritic cells are required
When looking at IRF8 CRISPR/Cas9 knock-out mutation in human in vitro induced pluripotent stem cells, it was noted that the generation of plasmacytoid DCs (pDCs) and DC1 cells driven by FLT3L, SCF, GM-CSF, and IL-4 (FSG4) was ablated but the generation of CD1c+ DC2s was unaffected [69]

Summary

Introduction

Cells with dendritic cell (DC) properties have been classified as plasmacytoid DCs (pDCs), as CD141+ DCs and as CD1c+ DCs [1,2,3]. Among the CD1c+ DCs there is higher expression for several monocyte-associated genes (CD14, CD115, MAFB, S100A8/9, CD163, and Ficolin1) in cells defined either as CD14+ cells or as CD5−. In order to appropriately address the question of lineage assignment of the subsets of CD1c+ DCs, approaches using a broad panel of different monocytes, macrophages, and dendritic cells are required.

Results

Conclusion