| Outline of Final Research Achievements |
In this study, we showed a novel antigen (Ab) delivery platform for cancer vaccines that delivers an encapsulated Ag to splenic marginal zone B cells via the aid of a PEGylated liposome (PEG-Lip) system. In mice, preimmunization with empty PEG-Lips triggered the efficient delivery of a subsequent dose of Ag-containing PEG-Lips, injected 3 day later, to the spleen. This immunization induced a cytotoxic T cells (CTL) response against OVA-expressing murine thymoma (EG7-OVA) cells and resulted in in vivo growth inhibition of subsequently inoculated EG7-OVA cells. However, this immunization required repeated immunizations to achieve their antitumor effect. Therefore, to improve their antitumor effect, an adjuvant, aGC, was incorporated into the OVA-PEG-Lips (aGC/OVA-PEG-Lips). As expected, a single immunization treatment efficiently triggered a potent CTL induction, resulting in a rejection of the development and a suppression of the growth of tumors that had already developed s.c.
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