title: Role of Th1-stimulating cytokines in bacillus Calmette-Guérin (BCG)-induced macrophage cytotoxicity against mouse bladder cancer MBT-2 cells.
abstract: Previously, we have demonstrated that macrophages exhibited cytotoxicity toward mouse bladder cancer MBT-2 cells upon bacille Calmette-Guérin (BCG) stimulation. In this study, we have investigated the role of Th1-stimulating cytokines in BCG-induced macrophage cytotoxicity. Thioglycollate-elicited peritoneal exudate cells (PECs) were used as a conventional source for macrophages and the induction of PEC effector functions (cytolytic activity and cytokine production) by BCG was evaluated in vitro. The BCG-activated PECs showed potent cytotoxicity and killed MBT-2 cells in a dose-dependent manner. Depletion of T cells, natural killer (NK) cells, or both, in PEC preparations exhibited a marginal or small reduction of MBT-2 cell killing, suggesting that macrophages played a primary role in PEC cytotoxicity. Transwell assays indicated that the maximal PEC cytotoxicity required both direct cell-cell contact and soluble factors such as interferon (IFN)-gamma and tumour necrosis factor (TNF)-alpha. Neutralizing endogenous cytokines interleukin (IL)-12, IL-18, IFN-gamma or TNF-alpha reduced PEC cytotoxicity by 38%, 22%, 15% and 94%, respectively. Supplementation of BCG with recombinant (r)IL-2, rIL-12 or rIL-18 increased PEC cytotoxicity by approximately twofold. Compared with control BCG for PEC stimulation, rBCGs expressing IL-2 or IL-18 showed enhanced MBT-2 cell killing by PECs. Increased cytokine production (IFN-gamma, TNF-alpha and IL-6) was also observed in rBCG-stimulated PEC cultures. Taken together, these results suggest that Th1-stimulating cytokines play an important role in BCG-induced macrophage cytotoxicity and that combination of BCG with selected Th1-stimulating cytokines, either supplemented or expressed by BCG, may enhance the effect of BCG in the treatment of bladder cancer patients.
authors.affiliation: Department of Urology, University of Iowa, Iowa City, IA 52242, USA. yi-luo@uiowa.edu
authors.forename: Y
authors.initials: Y
authors.lastname: Luo
authors.forename: H
authors.initials: H
authors.lastname: Yamada
authors.forename: D P
authors.initials: DP
authors.lastname: Evanoff
authors.forename: X
authors.initials: X
authors.lastname: Chen
mesh_terms: D000818:Animals; D001500:BCG Vaccine / Q000276:immunology*; D016923:Cell Death / Q000276:immunology; D016207:Cytokines / Q000096:biosynthesis / Q000276:immunology; D003602:Cytotoxicity, Immunologic; D005260:Female; D008262:Macrophage Activation / Q000276:immunology; D017737:Macrophages, Peritoneal / Q000276:immunology*; D051379:Mice; D008809:Mice, Inbred C3H; D011994:Recombinant Proteins / Q000276:immunology; D018417:Th1 Cells / Q000276:immunology*; D014407:Tumor Cells, Cultured; D015854:Up-Regulation / Q000276:immunology; D001749:Urinary Bladder Neoplasms / Q000276:immunology / Q000473:pathology*
chemical_list: D001500:BCG Vaccine; D016207:Cytokines; D011994:Recombinant Proteins