Fast DNA Vaccination Strategy Elicits a Stronger Immune Response Dependent on CD8(+)CD11c(+) Cell Accumulation

Conventional DNA vaccine strategies usually employ a regimen of immunizations at 2-week or longer intervals to induce effective memory cell-dependent immune responses. Clinical cancer treatment requires a faster immunization strategy to contend with tumor progression. In this study, a novel fast immunization strategy was established, wherein a DNA vaccine was intramuscularly administered on days 0, 2, and 5 in a murine lung cancer model. Effector cells peaked 7 to 10 days after the last vaccination. Compared with traditional 2-week-interval immunization strategies, antigen-specific cytolysis and INF-γ secretion were significantly enhanced under the fast vaccination approach. As a result, the rapidly administered DNA vaccine elicited stronger and more prompt antitumor effects. The probable underlying mechanism of fast immunization was the accumulation of CD8(+)CD11c(+) antigen-presenting cells at the injection site, which enhanced subsequent antigen presentation. In conclusion, the fast DNA vaccination strategy shortened vaccination time to 5 days and elicited a stronger antitumor immune response.