An innovative strategy to enhance cross-presentation in dendritic cell-based vaccines

Immunotherapy has emerged as an important approach for combating cancer. Dendritic cell (DC)-based vaccines are a promising form of immunotherapy because of their ability to induce tumor antigen-specific T cells. Although there are many methods for preparing DC-based vaccines using full-length proteins, cell-penetrating peptides (CPP) have shown success in their ability to deliver whole proteins into DCs and induce antitumor immunity via cross-presentation to CD8+ T cells. This process, however, is limited by the necessity to covalently link the protein of interest to CPP. In our study, we use LAH4, a histidine-rich amphipathic CPP previously used as a DNA transfection reagent, as a novel method of protein delivery that does not require covalent linkage. Our results show that LAH4 mixed with protein could form complexes detectable by immunofluorescence and flow cytometry. We have also shown that LAH4 were capable of complexing with a variety of proteins to bind with different cell types. Furthermore, our data indicate that LAH4 cell binding is partially mediated through surface heparan sulfates. More importantly, DCs incubated with LAH4 mixed with a model antigen, chicken ovalbumin (OVA) protein, were able to significantly activate OVA-specific OT1 T cells compared to OVA protein alone. Thus, we have demonstrated that LAH4 is able to transduce whole protein into cells and has potential to be used as a novel strategy in improving DC cross-presentation in tumor immunotherapy.