CD11c+ blood dendritic cells induce antigen-specific cytotoxic T lymphocytes with similar efficiency compared to monocyte-derived dendritic cells despite higher levels of MHC class I expression.

Dendritic cell (DC) immunotherapy for cancer has shown promising results in phase I and II clinical trials. Most studies have used monocyte-derived DCs (MoDCs) but their poor migratory capacity in vivo has emerged as a key issue. The natural circulating peripheral blood CD11c+ DC precursors (BDCs) may be an attractive alternative to MoDCs, as they can be isolated rapidly in sufficient quantities, and have superior migratory and T helper-1-inducing capacity in vitro. We performed the first comparative analysis of the ability of autologous BDCs and MoDCs in healthy donors to induce tumor-specific cytotoxic T lymphocytes (CTLs). BDCs expressed significantly higher levels of major histocompatibility complex class I and CD83 in the absence of exogenous stimuli compared with MoDCs. After activation with polyinosinic-polycytidylic acid, BDCs expressed higher levels of major histocompatibility complex class I, CD40, CD80, and CD83, and secreted higher levels of tumor necrosis factor-alpha, interleukin (IL)-1beta, IL-6, and IL-8 compared with MoDCs. Despite these differences, both preparations secreted similar levels of IL-12 in response to polyinosinic-polycytidylic acid and, importantly, induced CTL responses of similar magnitude and affinity against influenza matrix protein and MART-1. The ability of BDCs to induce efficient CTL responses, combined with their migratory capacity, makes them an appealing alternative to be investigated in clinical immunotherapy research protocols.