title: Dendritic cell-based vaccines suppress metastatic liver tumor via activation of local innate and acquired immunity.
abstract: BACKGROUND
  Dendritic cell (DC)-based vaccines have been applied clinically in the setting of cancer, but tumor-associated antigens (TAAs) have not yet been enough identified in various cancers. In this study, we investigated whether preventive vaccination with unpulsed DCs or peptide-pulsed DCs could offer anti-tumor effects against MC38 or BL6 liver tumors.
  
  
  METHODS
  Mice were subcutaneously (s.c.) immunized with unpulsed DCs or the recently defined TAA EphA2 derived peptide-pulsed dendritic cells (Eph-DCs) to treat EphA2-positive MC38 and EphA2-negative BL6 liver tumors. Liver mononuclear cells (LMNCs) from treated mice were subjected to (51)Cr release assays against YAC-1 target cells. In some experiments, mice were injected with anti-CD8, anti-CD4 or anti-asialo GM1 antibody to deplete each lymphocyte subsets.
  
  
  RESULTS
  Immunization with unpulsed DCs displayed comparable efficacy against both MC38 and BL6 liver tumors when compared with Eph-DCs. Both DC-based vaccines significantly augmented the cytotoxicity of LMNCs against YAC-1 cells. In vivo antibody depletion studies revealed that NK cells, as well as, CD4+ and CD8+ T cells play critical roles in the anti-tumor efficacy associated with either DC-based modality. Tumor-specific cytotoxic T lymphocyte (CTL) activity was generally higher if mice had received Eph-DCs versus unpulsed DCs. Importantly, the mice that had been protected from MC38 liver tumor by either unpulsed DCs or Eph-DCs became resistant to s.c. MC38 rechallenge, but not to BL6 rechallenge.
  
  
  CONCLUSIONS
  These results demonstrate that unpulsed DC vaccines might serve as an effective therapy for treating metastatic liver tumor, for which TAA has not yet been identified.
authors.affiliation: Department of Gastroenterology and Hepatology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan. syamaguc@gh.med.osaka-u.ac.jp
authors.forename: Shinjiro
authors.initials: S
authors.lastname: Yamaguchi
authors.forename: Tomohide
authors.initials: T
authors.lastname: Tatsumi
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Takehara
authors.forename: Akira
authors.initials: A
authors.lastname: Sasakawa
authors.forename: Hayato
authors.initials: H
authors.lastname: Hikita
authors.forename: Keisuke
authors.initials: K
authors.lastname: Kohga
authors.forename: Akio
authors.initials: A
authors.lastname: Uemura
authors.forename: Ryotaro
authors.initials: R
authors.lastname: Sakamori
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Ohkawa
authors.forename: Norio
authors.initials: N
authors.lastname: Hayashi
mesh_terms: D000818:Animals; D000951:Antigens, Neoplasm / Q000276:immunology; D019496:Cancer Vaccines / Q000276:immunology* / Q000627:therapeutic use*; D003713:Dendritic Cells / Q000276:immunology / Q000637:transplantation*; D005260:Female; D005434:Flow Cytometry; D007113:Immunity, Innate; D007694:Killer Cells, Natural / Q000276:immunology; D008113:Liver Neoplasms / Q000276:immunology* / Q000628:therapy*; D008214:Lymphocytes / Q000276:immunology; D051379:Mice; D036104:Receptor, EphA2 / Q000276:immunology
chemical_list: D000951:Antigens, Neoplasm; D019496:Cancer Vaccines; D036104:Receptor, EphA2