title: Activation of tumor-specific T lymphocytes by radio-frequency ablation of the VX2 hepatoma in rabbits.
abstract: Radio-frequency ablation (RFA) is used as a minimally invasive treatment for inoperable hepatic tumors. Immunological reactions secondary to RFA may play a role in the observed tumor control. In our study, the VX2 carcinoma was implanted into the liver of rabbits. After 3 weeks, tumors were treated with RFA or were left untreated. Peripheral blood lymphocytes were harvested before tumor implantation, 2 weeks postoperatively and at 2-week intervals thereafter. T cells were stimulated with lysates of either tumor tissue or nontumorous liver loaded on autologous antigen-presenting cells and their stimulation index was determined by [(3)H]thymidine incorporation. A 3-fold increase over background or controls was considered significant. Stimulation with phytohemagglutinin served as a positive control. The animals were necropsied, and liver and tumor tissue were analyzed immunohistologically for T-cell infiltration. T cells from tumor-bearing (n = 9) and RFA-treated (n = 11) animals were investigated in a follow-up study. The mean postoperative observation was 45 days. All of the 11 RFA-treated animals exhibited circulating T cells activated specifically toward tumor antigens throughout the observation period, which was accompanied by dense T-cell infiltration. In contrast, T cells of untreated tumor-bearing rabbits showed no reaction and only sparse T cell infiltration. We concluded that RFA induces a tumor-specific T-cell reaction in the otherwise unreactive tumor-bearing host, apparently overcoming immune tolerance and leading to the presentation of otherwise cryptic tumor antigens. Therefore, in addition to destroying tumor tissue, RFA induces an immune response against tumor antigens that may be exploited in multimodal antitumor strategies.
authors.affiliation: Department of Medicine I, Friedrich-Alexander University, Erlangen-Nuernberg, Ulmenweg 18, 91054 Erlangen, Germany.
authors.forename: Thaddäus Till
authors.initials: TT
authors.lastname: Wissniowski
authors.forename: Johannes
authors.initials: J
authors.lastname: Hänsler
authors.forename: Daniel
authors.initials: D
authors.lastname: Neureiter
authors.forename: Markus
authors.initials: M
authors.lastname: Frieser
authors.forename: Stefan
authors.initials: S
authors.lastname: Schaber
authors.forename: Birgit
authors.initials: B
authors.lastname: Esslinger
authors.forename: Reinhard
authors.initials: R
authors.lastname: Voll
authors.forename: Deike
authors.initials: D
authors.lastname: Strobel
authors.forename: Eckhart G
authors.initials: EG
authors.lastname: Hahn
authors.forename: Detlef
authors.initials: D
authors.lastname: Schuppan
authors.forename: Thädaus Till
authors.initials: TT
authors.lastname: Wissniowski
authors.forename: Johannes
authors.initials: J
authors.lastname: Hünsler
mesh_terms: D000818:Animals; D000951:Antigens, Neoplasm / Q000276:immunology; D017115:Catheter Ablation / Q000379:methods*; D008114:Liver Neoplasms, Experimental / Q000276:immunology* / Q000601:surgery*; D008213:Lymphocyte Activation / Q000276:immunology; D016246:Lymphocytes, Tumor-Infiltrating / Q000276:immunology; D011817:Rabbits; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D000951:Antigens, Neoplasm