Dendritic　cell-based　immunotherapy,　in　which　the　antigen　is　effectively　delivered　to　dendritic　cells　and　then　the　dendritic　cells　stimulated　by　the　antigen　migrate　to　draining　lymph　nodes　(DLNs)　to　induce　the　CD8+　T-cell　immune　response,　shows　great　promise　for　tumor　immunotherapy.　In　this　study,　we　used　coassembled　nanoparticles　formed　by　Trp2　antigen　and　the　conjugates　of　short-chain　poly(ethylene　glycol)　(PEG)　and　pyropheophorbide-A　(PPa)　(Trp2/PPa-PEGm)　to　deliver　Trp2　to　DCs.　Intrinsically　self-chelating　64Cu　of　coassemblies　could　be　used　to　sensitively　image　the　migration　of　DCs　in　vivo　by　positron　emission　tomography　(PET)　imaging.　The　coassemblies　of　the　Trp2　antigen　were　efficiently　engulfed　by　DCs　without　causing　DC　cytotoxicity　in　vitro　and　induced　DC　maturation.　After　injection　of　DCs　labeled　by　coassemblies　of　the　Trp2　antigen,　the　homing　of　DCs　to　DLNs　in　vivo　could　be　sensitively　observed　by　PET　imaging.　The　C57BL/6　mice　injected　with　DCs　containing　the　Trp2/PPa-PEGm　NP　showed　antigen-specific　immune　responses　including　enhanced　interferon-γ(IFN-γ)　production,　splenocyte　proliferation,　and　percentage　of　IFN-γ-secreting　CD8+　T　cells.　In　addition,　C57BL/6　mice　inoculated　with　B16-F10　tumor　cells　showed　delayed　tumor　growth　after　immunization　with　the　Trp2/PPa-PEGm　NP-labeled　DC　vaccine　and　enhanced　infiltration　of　CD8+　T　cells　in　tumors.　©　2021　American　Chemical　Society.