Immune Complexes Mimicking Synthetic Vaccine Nanoparticles for Enhanced Migration and Cross‐Presentation of Dendritic Cells

The well‐designed activation of dendritic cells (DCs) by enhancing the delivery of antigens and immunostimulatory adjuvants into DCs is a key strategy for efficient cancer immunotherapy. Antigen‐antibody immune complexes (ICs) are known to directly bind to and cross‐link Fc‐gamma receptors (FcγRs) on DCs, which induce enhanced migration of DCs to draining lymph nodes through the up‐regulation of the chemokine receptor CCR7 and cross‐presentation inducing cytotoxic T lymphocyte (CTL) response against tumor antigen. In this study, ICs mimicking synthetic vaccine nanoparticles (NPs) are designed and synthesized by the coating of poly (lactic‐co‐glycolic acid) (PLGA) NPs containing adjuvant (CpG oligodeoxynuleotides (ODNs) as toll‐like receptor 9 ligands) with ovalbumin (OVA) proteins (as model antigens) and by the formation of OVA–OVA antibody ICs. Through the combination of FcγRs‐mediated efficient antigen uptake and CpG ODNs‐based immunostimulation, the secretion of TNF‐α (12.3‐fold), IL‐6 (7.29‐fold), and IL‐12 (11‐fold), homing ability to lymph nodes (7.5‐fold), and cross‐presentation (83.8‐fold IL‐2 secretion) are dramatically increased in DCs treated with PLGA(IC/CpG) NPs. Furthermore, mice vaccinated with DCs treated with PLGA(IC/CpG) NPs induced significant tumor (EG7‐OVA) growth inhibition as well as prolonged survival through CTL‐mediated enhanced cytotoxicity, antigen‐specific responses, and IFN‐γ secretion.