Tumor cell-derived exosome-targeted dendritic cells stimulate stronger CD8+ CTL responses and antitumor immunities.

Tumor cell-derived exosomes (TEX) have been widely used to induce antitumor immune responses in animal models and clinical trials. However, the efficiency of the antitumor immunity that is induced by TEX is still relatively weak. In this study, we compared the antitumor immunities between EG7 tumor cell-derived exosomes (EXO(EG7)) and EXO(EG7)-targeted dendritic cells (DC(EXO)). We found that EXO(EG7) harbored OVA and peptide major histocompatibility complex I (pMHC-I), which were expressed on its parental EG7 tmor cells, and they could transfer OVA and pMHC-I to dendritic cells (DCs) in vitro. DC(EXO) could more efficiently induce antitumor immunity than EXO(EG7). In addition, we showed that the immune stimulatory effects of EXO(EG7) were dependent on the host DCs and, whereas those of DC(EXO) were not, indicating the important role of the host DCs in TEX vaccines. Taken together, TEX-targeted DCs may be more effective for EXO-based vaccines for the induction of antitumor immunity.