title: Augmenting major histocompatibility complex class I expression by murine tumors in vivo enhances antitumor immunity induced by an active immunotherapy strategy.
abstract: OBJECTIVE
  Tumors down-regulate major histocompatibility complex class I expression, escaping recognition by the cellular immune response. We hypothesized that augmentation of tumor cell class I expression by interferon-gamma would enhance the cellular antitumor immune response and cure rate of an active immunotherapy strategy.
  
  
  METHODS
  B16.F10 tumor cells were exposed to interferon-gamma in culture, and class I expression was quantified using flow cytometry. Syngeneic mice bearing established tumors were injected with interferon-gamma (5000 U, intraperitoneal), and class I expression was assessed using immunohistochemistry. Tumor-specific cytotoxic T lymphocytes were induced in mice by an intratumoral injection of AdCD40L (5 x 10(10) particles), an adenovirus gene transfer vector-based immunotherapy strategy previously demonstrated to augment cellular antitumor immunity. A conjugate-formation assay and the enzyme-linked immunospot assay were used to evaluate the binding and activation of cytotoxic T lymphocytes, respectively. Interferon-gamma was administered to tumor-bearing mice concomitantly with intratumoral AdCD40L. End points measured included the frequencies of cytotoxic T lymphocytes using the enzyme-linked immunospot assay, tumor size, and mouse survival. The role of class I expression was further evaluated by monoclonal antibody blockade in both in vitro and in vivo experiments.
  
  
  RESULTS
  B16.F10 cells exposed to interferon-gamma expressed significantly more class I, both in vitro and in vivo, and were able to bind to and activate cytotoxic T lymphocytes more efficiently than untreated cells. Cytotoxic T-lymphocyte frequencies, tumor regression, and the cure rate induced by AdCD40L were augmented by the addition of a single dose of interferon-gamma in tumor-bearing mice. These in vitro and in vivo effects of interferon-gamma were attenuated by class I monoclonal antibody blockade.
  
  
  CONCLUSIONS
  Up-regulation of class I expression using interferon-gamma enhances the cellular antitumor immune response and cure rate of AdCD40L, an active immunotherapy strategy. This approach may be useful for human tumors that lack class I expression.
authors.affiliation: Department of Cardiothoracic Surgery, Weill Medical College of Cornell University, New York, NY 10021, USA.
authors.forename: Robert E
authors.initials: RE
authors.lastname: Merritt
authors.forename: Reiko E
authors.initials: RE
authors.lastname: Yamada
authors.forename: Ronald G
authors.initials: RG
authors.lastname: Crystal
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Korst
mesh_terms: D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000187:drug effects / Q000276:immunology; D018827:Carcinoma, Lewis Lung / Q000276:immunology* / Q000378:metabolism / Q000628:therapy*; D003602:Cytotoxicity, Immunologic / Q000187:drug effects / Q000276:immunology; D004306:Dose-Response Relationship, Immunologic; D004359:Drug Therapy, Combination; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005805:Genes, MHC Class I / Q000187:drug effects / Q000276:immunology*; D006183:H-2 Antigens / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D007111:Immunity, Cellular / Q000187:drug effects / Q000276:immunology; D016233:Immunotherapy, Active; D007371:Interferon-gamma / Q000008:administration & dosage; D008175:Lung Neoplasms / Q000276:immunology* / Q000378:metabolism / Q000628:therapy*; D008213:Lymphocyte Activation / Q000187:drug effects / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D023421:Models, Animal; D011994:Recombinant Proteins; D013602:T-Lymphocytes, Cytotoxic / Q000187:drug effects / Q000276:immunology; D016896:Treatment Outcome; D014407:Tumor Cells, Cultured; D015854:Up-Regulation / Q000276:immunology
chemical_list: D006183:H-2 Antigens; C032876:H-2Kb protein, mouse; D011994:Recombinant Proteins; D007371:Interferon-gamma