Transcriptional comparison of in vitro and in vivo generated human dendritic cells

Dendritic cells (DC) are antigen presenting cells controlling T cell activation. In human, the diversity, ontogeny and functional capabilities of DC subsets are not fully understood. Here, we identified circulating CD88-CD1c+CD163+ DC (termed as DC3) as an immediate precursor of inflammatory CD88-CD14+CD1c+CD163+FcεRI+ DC. DC3 develop via a specific pathway, independent from the cDC-restricted (CDP) and monocyte-restricted (cMoP) progenitors, and are activated by GM-CSF. As classical DC, but unlike monocytes, DC3 drove the activation of naïve T cells. In vitro, DC3 displayed a distinctive ability to prime CD8+ T cells expressing a tissue-homing signature and the epithelial homing alpha-E integrin (CD103) through transforming growth factor-b (TGF-β) signaling. In vivo, DC3 infiltrated luminal breast cancer primary tumors and DC3 infiltration correlated positively with CD8+CD103+CD69+ tissue-resident memory T cells. Altogether, these findings define DC3 as a lineage of inflammatory DC endowed with a strong potential to regulate tumor immunity. Blood monocytes, pDC, AS-DC, CD5+ DC2, CD5- DC2 and DC3 were isolated from healthy donor. Monocytes, DC2 and DC3 were stimulated by a TLR agonist coktail. Naive CD8+ T cells and CXCR3+CD103- and CXCR3+CD103- CD8+ T cells were sorted by flow cytometry at day 5 of in vitro coculture with blood DC3. All cell types were analyzed in triplicates with 200 to 1000 cells per subset.