Immunization with dendritic cells (DCs) pulsed with tumor antigen can activate tumor-specific cytotoxic T lymphocytes (CTL), which is responsible for tumor protection and regression. In this study, we examined whether DCs pulsed with necrotic tumor lysates can efficiently prevent malignant melanoma tumor cell metastasis to the lung. DCs derived from mouse bone marrow were found to produce remarkably elevated levels of IL-12 after being pulsed with the tumor lysates. Moreover, immunization with these DCs induced CTL activation and protected mice from metastasis development by intravenously inoculated tumor cells. In addition, these DCs activated NK cells in vitro in a contact-dependent manner, and induced NK activities in vivo. Furthermore, NK cell depletion before DC vaccination significantly reduced the tumor-specific CTL activity, IFN-g production, and IFN-gamma- inducible gene expression, and eventually interfered with the antitumor effect of tumor-pulsed DCs. Finally, similar findings with respect to NK cell dependency were obtained in the C57BL/ 6J-bg/bg mice, which have severe deficiency in cytolytic activity of NK cells. These data suggest that the antitumor effect elicited by DC vaccination, at least in a B16 melanoma model, requires the participation of both cytolytic NK and CD8+ T cells. The findings of this study would provide important data for the effective design of DC vaccines for cancer immunotherapy.
Animals ; Antigen Presentation/immunology ; CD8-Positive T-Lymphocytes/immunology ; Cancer Vaccines/*therapeutic use ; Cell Line, Tumor ; Cytokines/biosynthesis/immunology ; Dendritic Cells/immunology/*transplantation ; Female ; Interferon Type II/biosynthesis/immunology ; Interleukin-12/biosynthesis/immunology ; Killer Cells, Natural/*immunology ; Lung Neoplasms/immunology/prevention & control/secondary ; Lymphocyte Activation/immunology ; Lymphocyte Depletion ; Melanoma, Experimental/immunology/secondary/*therapy ; Mice ; Mice, Inbred C57BL ; Monocyte Chemoattractant Proteins/biosynthesis/immunology ; Research Support, Non-U.S. Gov't ; T-Lymphocytes, Cytotoxic/immunology

OBJECTIVETo investigate the enhanced effect of bone marrow-derived dendritic cells (DC) pulsed with SVYDFFVWL, a MHC class I peptide located in 180-188 amino acid residues of human melanoma-associated antigen tyrosinase- related protein 2 ( hTRP2) on the immunity against melanomas elicited by adenovirus encoding hTRP2 (Ad hTRP2).

METHODSThe mice were intradermally immunized with Ad hTRP2, and three weeks later with Ad hTRP2 or DC/SVYDFFVWL once more. Analysis of CTL killing activity and IFN-gamma-producing CD8 + T cells in the total CD8 + T cells of spleen were made using in vivo CTL and intracellular staining of IFN-gamma, respectively. Additionally, the survival of mice was checked after the subcutaneous inoculation with mouse melanoma B16. F10 cells.

RESULTSThe 6 h CTL killing and IFN-gamma producing CD8 +T cells in the total CD8 ' T cells of spleens were 68. 40%+/-5. 50% and 0. 67%+/-0.16% in Ad hTRP2 (priming)-Ad hTRP2 (boosting) group,28. 50%+/-6.40% and 0.22%+/-0.07% in DC/SVYDFFVWL (priming)-DC/ SVYDFFVWL (boosting) group,and 98. 90%+/-0.90% and 1.05%+/-0.21% in Ad hTRP2 (priming)-DC/ SVYDFFVWI, (boosting) group, respectively. In the tumor-bearing model, none of mice survived in DC/SVYDFFVWL (priming)-DC/SVYDFFVWL (boosting) group, and just only 40% of mice were tumor-free in Ad hTRP2 (priming) -Ad hTRP2 (boosting) group, whereas 100% of mice survived in Ad hTRP2 (priming)-DC/SVYDFFVWL (boosting) group.

CONCLUSIONBoosting with DC/ SVYDFFVWL can significantly enhance the immunity against melanomas elicited by priming with Ad hTRP2, indicating that first priming with Ad hTRP2 and then boosting with DC/SVYDFFVWL is a potentially effective regimen for overcoming the disadvantage that anti-tumor immune response can not be significantly increased by readministration of adenovirus.

Adenoviridae ; genetics ; Animals ; CD8-Positive T-Lymphocytes ; immunology ; Cancer Vaccines ; immunology ; Cell Line, Tumor ; Cells, Cultured ; Cytotoxicity Tests, Immunologic ; Dendritic Cells ; cytology ; immunology ; Female ; Genetic Vectors ; genetics ; Humans ; Immunization, Secondary ; methods ; Intramolecular Oxidoreductases ; immunology ; Melanoma, Experimental ; immunology ; pathology ; therapy ; Membrane Proteins ; immunology ; Mice ; Mice, Inbred C57BL ; Peptide Fragments ; immunology ; Survival Analysis ; T-Lymphocytes, Cytotoxic ; immunology

OBJECTIVETo investigate the inhibitory effect of DNA vaccine immunization on neu-overexpressed melanoma growth in prophylactic treatment and anti-lung-metastasis experiments in C57BL/6 mice.

METHODSpcDNA-neu transfected into B16F10 with transfection reagent Fugene 6, neu-overexpressed cell clone B16F10-neu was selected with limited dilution method. The growth curve was drawn to analyse its proliferating character in vitro. With Helios gene gun system, DNA vaccine pWRG-neu was immunized to 8-week-old C57BL/6 mice in the shaved abdominal skin for 3 times at two-weekly interval. After immunization, the life span was analyzed. Using MTT assay, the cytolysis activity of the DNA immunized mice spleen cells was compared.

RESULTSOne clone of neu-overexpressed B16F10-neu was selected and its proliferating character was the same as B16F10 and B16F10-pcDNA. In prophylactic, treatment and anti-lung-metastasis experiments, gene gun-mediated pWRG-neu immunization could exhibit antitumor effects. The growth and metastasis of neu-overexpressed melanoma was reduced dramatically. The spleen cells of the immuned mice showed cytotoxic T lymphocyte (CTL) activity.

CONCLUSIONGene gun-mediated gene transfer is effective and practicable. DNA vaccine pWRG-neu is potent in preventing subsequent tumor cells challenge, inhibiting the tumor growth and metastasis.

Animals ; Biolistics ; Cell Line, Tumor ; Cytotoxicity, Immunologic ; Genes, erbB-2 ; Immunization ; Lung Neoplasms ; prevention & control ; secondary ; Melanoma, Experimental ; metabolism ; pathology ; therapy ; Mice ; Mice, Inbred C57BL ; Neoplasm Transplantation ; Plasmids ; Receptor, ErbB-2 ; metabolism ; T-Lymphocytes, Cytotoxic ; immunology ; Vaccines, DNA

Transduction of cytokine gene into tumor cells is a promising method of tumor therapy, but the value is limited by accompanying side effects. To focus antitumor immune response to tumor antigen-specific CTL, we developed an antitumor vaccine by transfecting modified IL-2 gene in a membrane-bound form (mbIL-2) into B16F10 melanoma cells. The mbIL-2 clone showed reduced tumorigenicity and metastatic ability, and inhibited metastasis and prolonged the survival of mice against B16F10 cells. The inhibition of B16F10 metastasis by mbIL-2 was accompanied by the increment of CD8+ T cells. The metastasis of mbIL-2 clone was significantly increased in the CD8+ T cell-depleted mice, but not in CD4+ T cell depleted mice. Spleen cells immunized with the mbIL-2 clone showed higher CTL activity towards B16F10 cells than those immunized with control cells. The size of CD8+ T cell population in the lung of mice injected with the mbIL-2 clone was markedly greater than that of mice injected with B16F10 cells, but there was no detectible change in CD4+ and CD8+ T cell populations of lymph nodes and spleen. These results suggest that when the mbIL-2 clone is introduced into the blood stream, it migrates mainly to lung and activates CD8+ T cells in situ, possibly by direct priming. Such a tumor vaccine may ameliorate the toxic side effects encountered with conventional cytokine gene therapy.
Animals ; CD4-Positive T-Lymphocytes ; CD8-Positive T-Lymphocytes/immunology ; Cancer Vaccines/*immunology ; Female ; *Genetic Engineering ; Interleukin-2/*genetics/metabolism ; Lung Neoplasms/*immunology/secondary/therapy ; Lymphocyte Activation ; Melanoma, Experimental/genetics/*immunology/*prevention & control ; Mice ; Mice, Inbred C57BL ; Research Support, Non-U.S. Gov't ; Spleen/immunology ; Survival Rate ; T-Lymphocytes, Cytotoxic/immunology ; Vaccination