title: More efficient induction of HLA-A*0201-restricted and carcinoembryonic antigen (CEA)-specific CTL response by immunization with exosomes prepared from heat-stressed CEA-positive tumor cells.
abstract: OBJECTIVE
  Tumor-derived exosomes are proposed as a new type of cancer vaccine. Heat shock proteins are potent Th1 adjuvant, and heat stress can induce heat shock protein and MHC-I expression in tumor cells, leading to the increased immunogenicity of tumor cells. To improve the immunogenicity of exosomes as cancer vaccine, we prepared exosomes from heat-stressed carcinoembryonic antigen (CEA)-positive tumor cells (CEA+/HS-Exo) and tested the efficacy of these exosomes in the induction of CEA-specific antitumor immunity.
  
  
  METHODS
  First, we identified the composition of CEA+/HS-Exo and observed their effects on human dendritic cell maturation. Then, we evaluated their ability to induce a CEA-specific immune response in vivo in HLA-A2.1/Kb transgenic mice and CEA-specific CTL response in vitro in HLA-A*0201+ healthy donors and HLA-A*0201+CEA+ cancer patients.
  
  
  RESULTS
  CEA+/HS-Exo contained CEA and more heat shock protein 70 and MHC-I and significantly induced dendritic cell maturation. Immunization of HLA-A2.1/Kb transgenic mice with CEA+/HS-Exo was more efficient in priming a CEA-specific CTL, and the CTL showed antitumor effect when adoptively transferred to SW480-bearing nude mice. Moreover, in vitro incubation of lymphocytes from HLA-A*0201+ healthy donors and HLA-A*0201+CEA+ cancer patients with CEA+/HS-Exo-pulsed autologous dendritic cells induces HLA-A*0201-restricted and CEA-specific CTL response.
  
  
  CONCLUSIONS
  Our results show that CEA+/HS-Exo has superior immunogenicity than CEA+/Exo in inducing CEA-specific CTL response and suggest that exosomes derived from heat-stressed tumor cells may be used as efficient vaccine for cancer immunotherapy.
authors.affiliation: Institute of Immunology, Zhejiang University, Hangzhou, People's Republic of China.
authors.forename: Shengming
authors.initials: S
authors.lastname: Dai
authors.forename: Tao
authors.initials: T
authors.lastname: Wan
authors.forename: Baomei
authors.initials: B
authors.lastname: Wang
authors.forename: Xiangyang
authors.initials: X
authors.lastname: Zhou
authors.forename: Fangming
authors.initials: F
authors.lastname: Xiu
authors.forename: Taoyong
authors.initials: T
authors.lastname: Chen
authors.forename: Yanfeng
authors.initials: Y
authors.lastname: Wu
authors.forename: Xuetao
authors.initials: X
authors.lastname: Cao
mesh_terms: D000818:Animals; D019496:Cancer Vaccines / Q000276:immunology* / Q000302:isolation & purification; D002272:Carcinoembryonic Antigen / Q000276:immunology*; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000276:immunology* / Q000473:pathology / Q000628:therapy; D003601:Cytotoxicity Tests, Immunologic; D003602:Cytotoxicity, Immunologic / Q000276:immunology; D015234:HLA-A Antigens / Q000235:genetics / Q000276:immunology*; D015789:HLA-A2 Antigen; D018840:HSP70 Heat-Shock Proteins / Q000276:immunology; D006358:Hot Temperature; D006801:Humans; D007114:Immunization; D016219:Immunotherapy, Adoptive; D007959:Lymphocyte Culture Test, Mixed; D051379:Mice; D008819:Mice, Nude; D008822:Mice, Transgenic; D013154:Spleen / Q000166:cytology / Q000276:immunology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D023041:Xenograft Model Antitumor Assays
chemical_list: D019496:Cancer Vaccines; D002272:Carcinoembryonic Antigen; D015234:HLA-A Antigens; C435939:HLA-A*02:01 antigen; D015789:HLA-A2 Antigen; D018840:HSP70 Heat-Shock Proteins