There are three major dendritic cell (DC) subsets in both human and mouse, plasmacytoid DCs (pDCs) and two types of conventional DCs (cDCs), cDC1s and cDC2s. cDC2s are important for polarizing CD4+ naive T cells into different subsets including Th1, Th2, Th17, Th22 and regulatory T cells (Tregs). In mice, cDC2s can be further divided into phenotypically and functionally distinct subgroups. However, subsets of human cDC2s have not been reported. In the present study, we showed that human blood CD1c+ conventional DCs (cDC2s) can be further separated into two subpopulations according to their CD5 expression status. Comparative transcriptome analyses showed that the CD5high DCs expressed higher levels of cDC2-specific genes, including IRF4, which is essential for the cDC2 development and its migration to lymph nodes. In contrast, CD5low DCs preferentially expressed monocyte-related genes, including the lineage-specific transcription factor MAFB. Furthermore, compared with CD5low subpopulation, CD5high subpopulation showed stronger migration toward CCL21 and overrepresentation among migratory DCs in lymph nodes. Additionally, the CD5high DCs induced naÃ¯ve T-cell proliferation more potently than the CD5low DCs. Moreover, CD5high DCs induced higher levels of IL-10-, IL-22- and IL-4-producing T-cell formation, whereas CD5low DCs induced higher levels of IFN-?-producing T-cell formation. Thus, we show that human blood CD1c+ cDC2s encompass two subsets that differ significantly in phenotype, gene expression, and functions. We propose that these two subsets of human cDC2s could potentially play contrasting roles in immunity or tolerance. Overall design: The mRNA profiles of two human blood CD1c+ conventional DCs (cDC2s) subpopulations, in triplicate.