Numerical defect of circulating dendritic cell subsets and defective dendritic cell generation from monocytes of patients with advanced melanoma

• Focus on circulating dendritic cells (DCs) and DC generation from monocytes in melanoma.
• A significant decrease in the absolute number of total DCs was found.
• The DC-decrease mainly affected plasmacytoid DCs in stage IV.
• Monocyte-DC generation was less efficient in advanced stages.
• Our findings may have implications for immunotherapeutic approaches.

The behaviour of circulating dendritic cells (DCs) and DC generation from monocytes in melanoma patients during the progression of disease have not been described.We report a significant decrease in the absolute number of total DCs, which mainly affects plasmacytoid DCs in stage IV. Additionally, monocyte-DC generation is less efficient in advanced stages, resulting in DCs that exhibit increased phagocytic capacity, potentially indicating a less mature state. These findings elucidate aspects of basic tumour-mediated immunosuppression, which may have implications for immunotherapeutic approaches, suggesting that the selection of patients for immunotherapy should also be made on the basis of their immune status.