Immunotherapy with tumor cell lysate-pulsed CD8α+ dendritic cells modulates intra-tumor and spleen lymphocyte subpopulations.

Using cellular adjuvants including dendritic cells (DCs) has provided a promising approach in immunotherapy of cancer. Our previous study showed that mice immunization with tumor cell lysate-pulsed DCs (TL-CD8α+DCs) could significantly suppress the tumor growth and increase mice survival. The aim of the present study was to investigate the impact of TL-CD8α+DC vaccine on intra-tumor and spleen lymphocyte subpopulations in tumor-bearing mice. ABalb/c mouse model of fibrosarcoma was used and changes in various lymphocyte subpopulations including CD4+, CD8+ and CD4+CD25+Foxp3+ T cells in mice immunized with TL-CD8α+ DCs were studied. The cytotoxic activity of the lymphocytes and tumor growth inhibitory rate were also measured. Immunotherapy with TL-CD8α+ DCs significantly enhanced both CD4+ and CD8+ lymphocytes, whereas decreased CD4+CD25+ Foxp3+ regulatory T cells as well as the tumor growth rate. There was also a decrease in the ratio of regulatory T cells to CD4+ and to CD8+ lymphocytes in both the tumor and spleen tissues as compared to that in the non-immunized control mice. Immunization with TL-CD8α+ DCs as well as CD8α+ DCs significantly increased the splenocytes cytotoxic activity by 45.1% and 18.2% of control, respectively. In conclusion, the current study indicated that TL-CD8α+ DCs can enhance tumor immunity against the fibrosarcoma by enhancing both the CD4+ and CD8+ lymphocytes and reducing regulatory T cells. This finding suggests the usefulness of TL-CD8α+DCs vaccine for cancer treatment.