title: Interleukin-21 gene transfection into mouse bladder cancer cells results in tumor rejection through the cytotoxic T lymphocyte response.
abstract: OBJECTIVE
  We developed the genetically modified mouse bladder carcinoma MBT2 (American Type Culture Collection, Manassas, Virginia), which secretes interleukin-21, to investigate the functional activities of interleukin-21 in tumor immunity.
  
  
  METHODS
  The IL-21 gene was cloned from activated T cells by reverse transcriptase-polymerase chain reaction, inserted into an expression vector and then introduced into MBT2 using Lipofectamine. Exogenous interleukin-21 was assayed in culture supernatants from transfectants using sandwich enzyme-linked immunoassay. Direct antitumor and tumor vaccine effects were investigated in syngeneic mice rendered immunodeficient by administration of the corresponding antibody.
  
  
  RESULTS
  MBT2 cells secreting interleukin-21 (MBT2/IL-21) were completely rejected when subcutaneously injected into syngeneic mice. MBT2/IL-21 proliferated only when CD8+ T cells were depleted, whereas MBT2/IL-21 proliferation was totally abrogated in mice depleted of CD4+ T cells, natural killer cells or interferon-gamma. Subcutaneous injection of MBT2/IL-21 treated with mitomycin C remarkably inhibited parental MBT2 tumor growth at the contralateral site. Cytotoxicity assays using splenocytes from mice that rejected MBT2/IL-21 and the immunohistochemical features of MBT2/IL-21 tumors confirmed that in situ production of interleukin-21 can elicit powerful antitumor activity through CD8+ T-cell activation.
  
  
  CONCLUSIONS
  Interleukin-21 production in situ elicits antitumor activity through the activation of CD8+ T cells in vivo.
authors.affiliation: Divisions of Urology and Dermatology, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, Japan. urofuru@med.kobe-u.ac.jp
authors.forename: Junya
authors.initials: J
authors.lastname: Furukawa
authors.forename: Isao
authors.initials: I
authors.lastname: Hara
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nagai
authors.forename: Akihisa
authors.initials: A
authors.lastname: Yao
authors.forename: Shuntaro
authors.initials: S
authors.lastname: Oniki
authors.forename: Masato
authors.initials: M
authors.lastname: Fujisawa
mesh_terms: D000818:Animals; D007378:Interleukins / Q000235:genetics*; D051379:Mice; D013602:T-Lymphocytes, Cytotoxic / Q000502:physiology*; D014162:Transfection; D014407:Tumor Cells, Cultured; D001749:Urinary Bladder Neoplasms / Q000235:genetics* / Q000276:immunology*; D000098546:Interleukin-21
chemical_list: D007378:Interleukins; D000098546:Interleukin-21