Antitumour activity mediated by CD4+ cytotoxic T lymphocytes against MHC class II-negative mouse hepatocellular carcinoma induced by dendritic cell vaccine and interleukin-12.
When BALA/c mice with BNL hepatocellular carcinoma (HCC) were treated with dendritic cells fused with BNL cells (DC/BNL) and recombinant murine interleukin (IL)-12, tumour development was significantly suppressed, whereas treatment with either DC/BNL or IL-12 alone did not show a tumour-suppressive effect. Antitumour activity induced by DC/BNL + IL-12 was abrogated by depletion of CD4+ T cells, but not by depletion of CD8+ T cells or natural killer cells. Splenic CD4+ T cells and CD8+ T cells from DC/BNL-treated mice showed cytotoxic activity against BNL cells after 3 days of incubation with DC/BNL, although BNL cells do not express major histocompatibility complex (MHC) class II molecules even after treatment with interferon (INF)-gamma. Furthermore, CD4+ T cells killed syngeneic-irrelevant CT26 cells and even allogeneic Hepa1-6 cells. This cytotoxicity was blocked by concanamycin A, but not by an anti-Fas ligand (FasL) monoclonal antibody, indicating that cytotoxic activity was mediated by perforin. Immunofluorescence microscopy demonstrated that abundant CD4+ T cells and MHC class II-positive macrophages, but not CD8(+) T cells, had infiltrated tumour tissue in mice treated with DC/BNL + IL-12. Flow cytometric analysis of tumour-infiltrating cells in mice treated with DC/BNL + IL-12 showed increases in CD4+ T cells and MHC class II+ CD11b+ cells but not in CD8+ T cells or MHC class I+ CD11b+ cells. Our results suggest that, in BNL-bearing mice treated with DC/BNL + IL-12, tumour macrophages activated by INF-gamma produced by IL-12-stimulated T cells might present BNL tumour antigens and activate DC/BNL-primed CD4+ cytotoxic T lymphocytes (CTLs) in a MHC class II-dependent manner, leading to perforin-mediated bystander killing of neighbouring MHC class II-negative tumour cells.
Homma
Sadamu
S
Department of Oncology, Institute of DNA Medicine, Jikei University School of Medicine, Tokyo, Japan. sahya@jikei.ac.jp
Komita
Hideo
H
Sagawa
Yukiko
Y
Ohno
Tsuneya
T
Toda
Gotaro
G
D000818:Animals; D000951:Antigens, Neoplasm / Q000276:immunology; D017209:Apoptosis / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D019496:Cancer Vaccines / Q000276:immunology*; D006528:Carcinoma, Hepatocellular / Q000276:immunology*; D045744:Cell Line, Tumor; D003602:Cytotoxicity, Immunologic / Q000276:immunology; D003713:Dendritic Cells / Q000276:immunology*; D053222:Fas Ligand Protein; D005260:Female; D005434:Flow Cytometry / Q000379:methods; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D018664:Interleukin-12 / Q000276:immunology*; D007694:Killer Cells, Natural / Q000276:immunology; D008114:Liver Neoplasms, Experimental / Q000276:immunology*; D008562:Membrane Glycoproteins / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D054353:Perforin; D052899:Pore Forming Cytotoxic Proteins; D013154:Spleen / Q000276:immunology
D000951:Antigens, Neoplasm; D019496:Cancer Vaccines; D053222:Fas Ligand Protein; C505658:Fasl protein, mouse; D000949:Histocompatibility Antigens Class II; D008562:Membrane Glycoproteins; D052899:Pore Forming Cytotoxic Proteins; D054353:Perforin; D018664:Interleukin-12