title: Stressed apoptotic tumor cells stimulate dendritic cells and induce specific cytotoxic T cells.
abstract: We have previously reported that stressed apoptotic tumor cells are more immunogenic in vivo than nonstressed ones. Using confocal microscopy we have confirmed our previous observation that heat-stressed apoptotic 12B1-D1 leukemia cells (BCR-ABL(+)) express HSP60 and HSP72 on their surface. To explore how the immune system distinguishes stressed from nonstressed apoptotic tumor cells, we analyzed the responses of dendritic cells to these 2 types of apoptotic cells. We found that nonstressed and heat-stressed apoptotic 12B1-D1 cells were taken up by dendritic cells in a comparable fashion. However, when stressed apoptotic 12B1-D1 cells were coincubated with immature dendritic cells for 24 hours, this resulted in greater up-regulation of costimulatory molecules (CD40, CD80, and CD86) on the surface of dendritic cells. Moreover, stressed apoptotic 12B1-D1 cells were more effective in stimulating dendritic cells to secrete interleukin-12 (IL-12) and in enhancing their immunostimulatory functions in mixed leukocyte reactions. Furthermore, we demonstrated that immunization of mice with stressed apoptotic 12B1-D1 cells induced the secretion of T helper-1 (T(H)1) profile of cytokines by spleen cells. Splenocytes from mice immunized with stressed apoptotic cells, but not nonstressed ones, were capable of lysing 12B1-D1 and the parental 12B1 line, but not a B-cell leukemia line, A20. Our data indicate that stressed apoptotic tumor cells are capable of providing the necessary danger signals, likely through increased surface expression of heat shock proteins (HSPs), resulting in activation/maturation of dendritic cells and, ultimately, the generation of potent antitumor T-cell responses.
authors.affiliation: Department of Pediatrics, Steele Memorial Children's Research Center, University of Arizona, Tucson 85724, USA.
authors.forename: Hanping
authors.initials: H
authors.lastname: Feng
authors.forename: Yi
authors.initials: Y
authors.lastname: Zeng
authors.forename: Michael W
authors.initials: MW
authors.lastname: Graner
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Katsanis
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000276:immunology*; D001854:Bone Marrow Cells; D019496:Cancer Vaccines / Q000008:administration & dosage / Q000494:pharmacology; D018834:Chaperonin 60 / Q000378:metabolism; D003713:Dendritic Cells / Q000276:immunology*; D050884:HSP72 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000378:metabolism; D006979:Hyperthermia, Induced; D007111:Immunity, Cellular / Q000187:drug effects; D007938:Leukemia / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D008213:Lymphocyte Activation / Q000276:immunology; D007959:Lymphocyte Culture Test, Mixed; D051379:Mice; D008807:Mice, Inbred BALB C; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D014407:Tumor Cells, Cultured
chemical_list: D019496:Cancer Vaccines; D018834:Chaperonin 60; D050884:HSP72 Heat-Shock Proteins; D006360:Heat-Shock Proteins