Tumor environments contain immunosuppressive antigen-presenting cells (APCs) that can prevent eradication of the tumor mediated by tumor-specific CD8+ T cells. In Cancer Cell, Broz et al. profile APC subsets in various tumors. Although tumor-associated macrophages are abundant at tumor margins, a rare CD103+ dendritic cell (DC) subset is also present in tumors. The CD103+ population responds to the cytokines GM-CSF and Flt3L. Analogous BDCA3+ DCs are present in human tumors. These CD103+ (BDCA3+) DCs express IL-12 and cross-present antigen to prime naive and activate effector CD8+ T cells. Ablation of these DCs in mice blunts tumor regression mediated by adoptive T cell therapy. Notably, retrospective analyses of human tumor gene-expression profiles positively correlate BDCA3+ DC signatures and patient prognosis. These findings suggest that boosting the frequency of this BDCA3+ DC subset might further enhance antitumor immunotherapy.

Cancer Cell (10 November 2014) doi:10.1016/j.ccell.2014.09.007