title: Optimization of dendritic cell loading with tumor cell lysates for cancer immunotherapy.
abstract: The immune response to cancer is critically determined by the way in which tumor cells die. As necrotic, stress-associated death can be associated with activation of antitumor immunity, whole tumor cell antigen loading strategies for dendritic cell (DC)-based vaccination have commonly used freeze-thaw "necrotic" lysates as an immunogenic source of tumor-associated antigens. In this study, the effect of such lysates on the ability of DCs to mature in response to well-established maturation stimuli was examined, and methods to enhance lysate-induced DC activation explored. Freeze-thaw lysates were prepared from murine tumor cell lines and their effects on bone marrow-derived DC maturation and function examined. Unmodified freeze-thaw tumor cell lysates inhibited the toll-like receptor-induced maturation and function of bone marrow-derived DCs, preventing up-regulation of CD40, CD86, and major histocompatibility complex class II, and reducing secretion of inflammatory cytokines [interleukin (IL)-12 p70, tumor necrosis factor-alpha, and IL-6]. Although IL-10 secretion was increased by lysate-pulsed DCs, this was not responsible for the observed suppression of IL-12. Although activation of the nuclear factor-kappaB pathway remained intact, the kinase activity of phosphorylated p38 mitogen-activated protein kinase was inhibited in lysate-pulsed DCs. Lysate-induced DC suppression was partially reversed in vitro by induction of tumor cell stress before lysis, and only DCs loaded with stressed lysates afforded protection against tumor challenge in vivo. These data suggest that ex vivo freeze-thaw of tumor cells does not effectively mimic in vivo immunogenic necrosis, and advocates careful characterization and optimization of tumor cell-derived vaccine sources for cancer immunotherapy.
authors.affiliation: Cancer Research UK Clinical Centre, St James's University Hospital, Leeds, UK.
authors.forename: Paul
authors.initials: P
authors.lastname: Hatfield
authors.forename: Alison E
authors.initials: AE
authors.lastname: Merrick
authors.forename: Emma
authors.initials: E
authors.lastname: West
authors.forename: Dearbhaile
authors.initials: D
authors.lastname: O'Donnell
authors.forename: Peter
authors.initials: P
authors.lastname: Selby
authors.forename: Richard
authors.initials: R
authors.lastname: Vile
authors.forename: Alan A
authors.initials: AA
authors.lastname: Melcher
mesh_terms: D000818:Animals; D017951:Antigen Presentation / Q000276:immunology / Q000528:radiation effects; D000951:Antigens, Neoplasm / Q000276:immunology / Q000528:radiation effects; D002454:Cell Differentiation / Q000276:immunology / Q000528:radiation effects; D016207:Cytokines / Q000276:immunology / Q000378:metabolism; D003713:Dendritic Cells / Q000276:immunology* / Q000473:pathology; D005260:Female; D005615:Freezing; D015972:Gene Expression Regulation, Neoplastic / Q000276:immunology / Q000528:radiation effects; D006358:Hot Temperature; D007167:Immunotherapy; D008213:Lymphocyte Activation / Q000276:immunology / Q000528:radiation effects; D008546:Melanoma, Experimental; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009336:Necrosis / Q000276:immunology; D009369:Neoplasms / Q000473:pathology / Q000628:therapy*; D011839:Radiation, Ionizing; D015398:Signal Transduction / Q000276:immunology / Q000528:radiation effects; D018417:Th1 Cells / Q000276:immunology; D048051:p38 Mitogen-Activated Protein Kinases / Q000276:immunology
chemical_list: D000951:Antigens, Neoplasm; D016207:Cytokines; D048051:p38 Mitogen-Activated Protein Kinases