Ex vivo-generated conventional dendritic cells type 1 and type 2 from blood progenitors induce potent antigen-specific T-cell immunity

While existing cancer therapies manage to reduce tumor burden, they often fail to produce durable or curative outcomes. Alternatively, cell-based approaches – particularly dendritic cell (DC) vaccines conceal the potential to elicit robust tumor-specific T-cell responses, equipping patients with T-cells capable of eradicating tumor cells and preventing future relapses. To date, most DC vaccines have been generated with monocyte-derived DCs (moDCs), nowadays considered less potent at priming T-cells than blood-derived DC subsets, arguing for the usage of blood DCs for vaccine development. However, their scarcity in blood has hindered their clinical application, limiting their use in DC-based vaccination trials. To overcome this limitation, we developed a protocol to generate clinically relevant quantities of conventional DC type 1 (cDC1s) and DC2-like cells (cDC2s) from progenitor cells isolated from peripheral blood without the need for G-CSF mobilization, enabling their use for autologous vaccinations. The protocol is feeder layer free, yields clinically relevant amounts of cDC1s and cDC2s-like cells, and can be translated into a GMP-compliant setup. The ex vivo-generated DCs resemble their natural counterparts, acquire a robust pro-inflammatory phenotype (e.g., CD83, CCR7, and IL-12p70), and efficiently expand pro-inflammatory T-cells (e.g., IFN-γ). Notably, in an in vitro immunization model, these DCs primed naive T-cells for the expansion of tumor-antigen-specific CD8 T-cells exhibiting strong immune-stimulating features (e.g., IFN-γ, CD107a). In summary, this study demonstrates that blood progenitors differentiate into cDC1 and cDC2-like cells capable of eliciting potent antigen-specific T-cell subsets, offering a promising avenue for the development of more effective DC-based cancer therapies.