title: Anti-4-1BB monoclonal antibody enhances rejection of large tumor burden by promoting survival but not clonal expansion of tumor-specific CD8+ T cells.
abstract: Anti-4-1BB monoclonal antibody (mAb) has been shown to induce antitumor immunity by a CD4/CD8-dependent mechanism, but its direct effect on tumor-specific CD8+ T cells in tumor rejection is unclear. Here we used transgenic CD8+ T cells against the unmutated tumor rejection antigen P1A to analyze whether this mAb can promote CD8+ T-cell function against large tumors in the absence of CD4+ T-helper cells. RAG-2(-/-) mice were challenged with P1A-expressing plasmacytoma J558. Once tumor size reached a diameter of 0.85-1.75 cm, mice were treated with P1A-specific CD8+ CTL (P1CTL) in conjunction with anti-4-1BB mAb or control IgG. All of the mice showed a partial regression of tumor, but mice treated with anti-4-1BB mAb exhibited markedly enhanced tumor rejection, delayed tumor progression, and prolonged survival. Correspondingly, we observed a substantial increase in the number of P1CTL in anti-4-1BB mAb-treated mice. Surprisingly, anti-4-1BB mAb did not accelerate division of the tumor-specific CD8+ T cells, and the increase in tumor-specific T-cell number was due to reduced activation-induced cell death. These results indicate that anti-4-1BB mAb can promote CD8+ T cell-mediated protection against large tumors in the absence of CD4+ T-cell help by promoting P1CTL survival without increasing initial clonal expansion.
authors.affiliation: Division of Cancer Immunology, Department of Pathology and Comprehensive Cancer Center, Ohio State University Medical Center, Columbus 43210, USA.
authors.forename: Kenneth F
authors.initials: KF
authors.lastname: May
authors.forename: Lieping
authors.initials: L
authors.lastname: Chen
authors.forename: Pan
authors.initials: P
authors.lastname: Zheng
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology* / Q000494:pharmacology; D015703:Antigens, CD; D000951:Antigens, Neoplasm / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D016923:Cell Death / Q000276:immunology; D004268:DNA-Binding Proteins / Q000235:genetics / Q000276:immunology; D018984:Epitopes, T-Lymphocyte / Q000276:immunology; D016219:Immunotherapy, Adoptive / Q000379:methods*; D008213:Lymphocyte Activation / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008822:Mice, Transgenic; D010954:Plasmacytoma / Q000276:immunology / Q000628:therapy; D017475:Receptors, Nerve Growth Factor / Q000276:immunology*; D018124:Receptors, Tumor Necrosis Factor / Q000276:immunology*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D014407:Tumor Cells, Cultured; D053261:Tumor Necrosis Factor Receptor Superfamily, Member 9
chemical_list: D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000951:Antigens, Neoplasm; D004268:DNA-Binding Proteins; D018984:Epitopes, T-Lymphocyte; C499308:Rag2 protein, mouse; D017475:Receptors, Nerve Growth Factor; D018124:Receptors, Tumor Necrosis Factor; C505715:Tnfrsf9 protein, mouse; D053261:Tumor Necrosis Factor Receptor Superfamily, Member 9; C064655:V(D)J recombination activating protein 2; C076546:tumor rejection antigen P815A, mouse