Co-immunization with L-Myc enhances CD8⁺ or CD103⁺ DCs mediated tumor-specific multi-functional CD8⁺ T cell responses

Renal carcinoma shows a high risk of invasion and metastasis without effective treatment. Herein, we developed a chitosan (CS) nanoparticle-mediated DNA vaccine containing an activated factor L-Myc and a tumor-specific antigen CAIX for renal carcinoma treatment. The subcutaneous tumor models were intramuscularly immunized with CS-pL-Myc/pCAIX or control vaccine, respectively. Compared with single immunization group, the tumor growth was significantly suppressed in CS-pL-Myc/pCAIX co-immunization group. The increased proportion and mature of CD11c⁺ DCs, CD8⁺ CD11c⁺ DCs and CD103⁺ CD11c⁺ DCs were observed in the splenocytes from CS-pL-Myc/pCAIX co-immunized mice. Furthermore, the enhanced antigen-specific CD8⁺ T lymphocyte proliferation, cytotoxic T lymphocyte (CTL) responses, and multi-functional CD8⁺ T cell induction were detected in CS-pL-Myc/pCAIX co-immunization group compared with CS-pCAIX immunization group. Of note, the depletion of CD8 T cells resulted in the reduction of CD8⁺ T cells or CD8⁺ CD11c⁺ DCs and the loss of anti-tumor efficacy induced by CS-pL-Myc/pCAIX vaccine, suggesting the therapeutic efficacy of the vaccine was required for CD8⁺ DCs and CD103⁺ DCs mediated CD8⁺ T cells responses. Likewise, CS-pL-Myc/pCAIX co-immunization also significantly inhibited the lung metastasis of renal carcinoma models accompanied with the increased induction of multi-functional CD8⁺ T cell responses. Therefore, these results indicated that CS-pL-Myc/pCAIX vaccine could effectively induce CD8⁺ DCs and CD103⁺ DCs mediated tumor-specific multi-functional CD8⁺ T cell responses and exert the anti-tumor efficacy. This vaccine strategy offers a potential and promising approach for solid or metastatic tumor treatment.