Exosome-loaded dendritic cells elicit tumor-specific CD8+ cytotoxic T cells in patients with glioma

In this study, we demonstrate that tumor-derived exosome-loaded dendritic cells can elicit a specific CD8(+) cytotoxic T-lymphocyte (CTL) response against autologous tumor cells in patients with malignant glioma. Exosomes were purified by ultrafiltration centrifugation and sucrose gradient ultracentrifugation. Exosomes had antigen-presenting molecules (MHC-I, HSP70), tumor antigen (MAGE-1) and adherent molecule (ICAM-1). After incubation with exosomes, the dendritic cells (DCs) could activate the T lymphocytes to become glioma-specialized CTL. The CTL had vigorous cytotoxicity to glioma cells as opposed to autologous lymphoblast cells. These data demonstrate that tumor exosome-loaded DC can be an effective tool in inducing glioma-specific CD8(+) CTLs able to kill autologous glioma cells in vitro. In conclusion, exosomes are a natural and new source of tumor-rejection antigens, opening up new avenues for immunization against glioma.