Secondary lymphoid tissue chemokine (SLC), which is expressed in T cell zones of secondary lymphoid organs, including the spleen and lymph nodes, strongly recruits both T lymphocytes and mature dendritic cells. As appropriate interaction of tumor-specific T cells and mature dendritic cells, equipped with tumor antigens, is a prerequisite for effective T cell immunity against established tumors, we mobilized lymphocytes and dendritic cells to tumor sites by intratumoral injection of secondary lymphoid tissue chemokine-Fc (SLC-Fc) fusion protein using the B16F10 murine melanoma model. Activation of dendritic cells, another prerequisite for the effective activation of naive tumor-specific T cells, was achieved by the addition of immunostimulatory cytosine-phosphorothioate-guanine oligodeoxynucleotide (CpG-ODN) into the tumor site. Intratumoral administration of SLC-Fc or CpG-ODN revealed antitumor effects against B16F10 murine melanoma grown in the subcutaneous space. Co-treatment of SLC-Fc and CpG-ODN displayed synergistic effects in reducing the tumor size. The synergistic antitumor effect in co-treatment group was correlated with the synergistic/additive increase in the infiltration of CD4+ T cells and CD11c+ dendritic cells in the tumor mass compared to the single treatment groups. These results suggest that the combined use of chemokines and adjuvant molecules may be a possible strategy in clinical tumor immunotherapy.
Animals ; Antigens, CD11c/immunology ; CD4-Positive T-Lymphocytes/immunology ; Cell Line, Tumor ; Cell Proliferation/drug effects ; Chemokine CCL21/*administration & dosage/pharmacology ; Chemotaxis, Leukocyte ; Dendritic Cells/immunology/metabolism ; Immunotherapy ; Injections, Intralesional ; Melanoma, Experimental/*immunology/*therapy ; Mice ; Mice, Inbred C57BL ; Oligodeoxyribonucleotides/*administration & dosage/pharmacology ; T-Lymphocytes/immunology/metabolism