title: Heat-shock induction of tumor-derived danger signals mediates rapid monocyte differentiation into clinically effective dendritic cells.
abstract: OBJECTIVE
  This study characterizes, biologically and clinically, a novel type of dendritic cells (DC) produced in the short term and called tumor antigen-presenting cells (TAPCells). In particular, we identified factors present in a lysate derived from heat-shocked allogeneic melanoma cells (TRIMEL) that are associated with TAPCells' enhanced capability to induce CD8(+) T-cell responses in vitro and in vaccinated melanoma patients.
  
  
  METHODS
  First, extensive phenotypic and functional characterization of TAPCells was performed, followed by vaccination of 45 melanoma patients with four doses of TAPCells over a period of 2 months. Specific delayed-type hypersensitivity (DTH) reaction was analyzed posttreatment and correlated with overall survival rates. Furthermore, heat-shock (HS)-induced factors present in TRIMEL and their effects on DC activation were identified and studied.
  
  
  RESULTS
  TRIMEL induced a committed, mature, DC-like phenotype in TAPCells and effectively activated melanoma-specific CD4(+) and CD8(+) T cells. Clinically, 64% of vaccinated patients showed positive DTH reaction against TRIMEL, and this was associated with improved overall survival. HS treatment of tumor cells increased calreticulin (CRT) plasma membrane translocation and induced the release of high-mobility group box 1 proteins (HMGB1). Both CRT and HMGB1 mobilization were associated with enhanced TAPCells' maturation and antigen (Ag) cross-presentation, respectively. DTH infiltration analysis revealed the presence of CD8(+)/CD45RO(+) T cells, thus confirming TAPCells' ability to cross-present Ags in vivo.
  
  
  CONCLUSIONS
  Our results indicate that lysates derived from heat-shocked tumor cells are an optimal source of tumor-associated Ags, which are crucial for the generation of DCs with improved Ag cross-presentation capacity and clinically effective immunogenicity.
authors.affiliation: Institute of Biomedical Sciences, Faculty of Medicine, Clinical Hospital, University of Chile, Santiago, Chile.
authors.forename: Raquel
authors.initials: R
authors.lastname: Aguilera
authors.forename: Carlos
authors.initials: C
authors.lastname: Saffie
authors.forename: Andrés
authors.initials: A
authors.lastname: Tittarelli
authors.forename: Fermín E
authors.initials: FE
authors.lastname: González
authors.forename: Marcos
authors.initials: M
authors.lastname: Ramírez
authors.forename: Diego
authors.initials: D
authors.lastname: Reyes
authors.forename: Cristián
authors.initials: C
authors.lastname: Pereda
authors.forename: Daniel
authors.initials: D
authors.lastname: Hevia
authors.forename: Tamara
authors.initials: T
authors.lastname: García
authors.forename: Lorena
authors.initials: L
authors.lastname: Salazar
authors.forename: Arturo
authors.initials: A
authors.lastname: Ferreira
authors.forename: Marcela
authors.initials: M
authors.lastname: Hermoso
authors.forename: Ariadna
authors.initials: A
authors.lastname: Mendoza-Naranjo
authors.forename: Carlos
authors.initials: C
authors.lastname: Ferrada
authors.forename: Paola
authors.initials: P
authors.lastname: Garrido
authors.forename: Mercedes N
authors.initials: MN
authors.lastname: López
authors.forename: Flavio
authors.initials: F
authors.lastname: Salazar-Onfray
mesh_terms: D000328:Adult; D000368:Aged; D000938:Antigen-Presenting Cells / Q000276:immunology / Q000378:metabolism; D000951:Antigens, Neoplasm / Q000276:immunology; D037282:Calreticulin / Q000276:immunology / Q000378:metabolism; D019496:Cancer Vaccines / Q000276:immunology* / Q000627:therapeutic use; D002454:Cell Differentiation / Q000276:immunology*; D045744:Cell Line, Tumor; D003713:Dendritic Cells / Q000276:immunology* / Q000378:metabolism; D005260:Female; D005434:Flow Cytometry; D024243:HMGB1 Protein / Q000276:immunology / Q000378:metabolism; D006358:Hot Temperature; D006801:Humans; D006968:Hypersensitivity, Delayed / Q000276:immunology; D016130:Immunophenotyping; D020014:K562 Cells; D053208:Kaplan-Meier Estimate; D008297:Male; D008545:Melanoma / Q000188:drug therapy / Q000276:immunology*; D008875:Middle Aged; D009000:Monocytes / Q000276:immunology* / Q000378:metabolism; D015398:Signal Transduction / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D055815:Young Adult
chemical_list: D000951:Antigens, Neoplasm; D037282:Calreticulin; D019496:Cancer Vaccines; D024243:HMGB1 Protein