The tissue dendritic cell (DC) compartment is heterogeneous, and the ontogeny and functional specialization of human tissue conventional DC (cDC) subsets and their relationship with monocytes is unresolved. Here we identify monocyte-related CSF1R⁺Flt3^- antigen presenting cells (APCs) that constitute about half of the cells classically defined as SIRPα⁺ DCs in the steady-state human small intestine. CSF1R⁺Flt3^- APCs express calprotectin and very low levels of CD14, are transcriptionally related to monocyte-derived cells, and accumulate during inflammation. CSF1R⁺Flt3^- APCs show typical macrophage characteristics functionally distinct from their Flt3⁺ cDC counterparts: under steady-state conditions they excel at antigen uptake, have a lower migratory potential, and are inefficient activators of naïve T cells. These results have important implications for the understanding of the ontogenetic and functional heterogeneity within human tissue DCs and their relation to the monocyte lineage.

中文翻译：

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转录分析显示单核细胞相关的巨噬细胞表型类似于人肠道中的 DC。

组织树突细胞 (DC) 区室是异质的，人体组织常规 DC (cDC) 子集的个体发育和功能特化及其与单核细胞的关系尚未解决。在这里，我们确定了单核细胞相关的 CSF1R ⁺ Flt3 ^-抗原呈递细胞 (APC)，它们构成了稳态人类小肠中大约一半的经典定义为 SIRPα ^{+ DC 的细胞。}CSF1R ⁺ Flt3 ^- APC 表达钙卫蛋白和极低水平的 CD14，与单核细胞衍生细胞转录相关，并在炎症期间积累。CSF1R ⁺ Flt3 ^- APC 表现出典型的巨噬细胞特征，在功能上不同于其 Flt3⁺ cDC 对应物：在稳态条件下，它们擅长抗原摄取，具有较低的迁移潜力，并且是幼稚 T 细胞的低效激活剂。这些结果对于理解人体组织 DC 内的个体发育和功能异质性及其与单核细胞谱系的关系具有重要意义。