title: Melanoma-reactive class I-restricted cytotoxic T cell clones are stimulated by dendritic cells loaded with synthetic peptides, but fail to respond to dendritic cells pulsed with melanoma-derived heat shock proteins in vitro.
abstract: Immunization with heat shock proteins (hsp) isolated from cancer cells has been shown to induce a protective antitumor response. The mechanism of hsp-dependent cellular immunity has been attributed to a variety of immunological activities mediated by hsp. Hsp have been shown to bind antigenic peptides, trim the bound peptides by intrinsic enzymatic activity, improve endocytosis of the chaperoned peptides by APCs, and enhance the ability of APCs to stimulate peptide-specific T cells. We have investigated the potential capacity of hsp70 and gp96 to function as a mediator for Ag-specific CTL stimulation in an in vitro model for human melanoma. Repetitive stimulation of PBLs by autologous DCs loaded with melanoma-derived hsp did not increase the frequency of T cells directed against immunodominant peptides of melanoma-associated Ags Melan-A and tyrosinase. In contrast, repeated T cell stimulation with peptide-pulsed DCs enhanced the number of peptide-specific T cells, allowing HLA/peptide multimer-guided T cell cloning. We succeeded in demonstrating that the established HLA-A2-restricted CTL clones recognized HLA-A2(+) APCs exogenously loaded with the respective melanoma peptide as well as melanoma cells processing and presenting these peptides in the context of HLA-A2. We were not able to show that these melanoma-reactive CTL clones were stimulated by autologous dendritic cells pulsed with melanoma-derived hsp. These results are discussed with respect to various models for proving the role of hsp in T cell stimulation and to recent findings that part of the immunological antitumor activities reported for hsp are independent of the chaperoned peptides.
authors.affiliation: Department of Hematology/Oncology, Klinikum rechts der Isar, Technical University of Munich, Ismaningerstrasse 22, D-81675 Munich, Germany.
authors.forename: Kristina
authors.initials: K
authors.lastname: Fleischer
authors.forename: Burkhard
authors.initials: B
authors.lastname: Schmidt
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Kastenmüller
authors.forename: Dirk H
authors.initials: DH
authors.lastname: Busch
authors.forename: Ingo
authors.initials: I
authors.lastname: Drexler
authors.forename: Gerd
authors.initials: G
authors.lastname: Sutter
authors.forename: Michael
authors.initials: M
authors.lastname: Heike
authors.forename: Christian
authors.initials: C
authors.lastname: Peschel
authors.forename: Helga
authors.initials: H
authors.lastname: Bernhard
mesh_terms: D017951:Antigen Presentation / Q000276:immunology; D000938:Antigen-Presenting Cells / Q000276:immunology / Q000378:metabolism; D000951:Antigens, Neoplasm / Q000276:immunology* / Q000378:metabolism; D002461:Cell Line, Transformed; D045744:Cell Line, Tumor; D002999:Clone Cells; D018920:Coculture Techniques; D003713:Dendritic Cells / Q000276:immunology* / Q000378:metabolism; D018984:Epitopes, T-Lymphocyte / Q000276:immunology / Q000378:metabolism; D015789:HLA-A2 Antigen / Q000096:biosynthesis / Q000276:immunology*; D018840:HSP70 Heat-Shock Proteins / Q000276:immunology / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D007371:Interferon-gamma / Q000096:biosynthesis / Q000378:metabolism; D020014:K562 Cells; D008213:Lymphocyte Activation / Q000276:immunology*; D018655:Lymphocyte Count; D058965:MART-1 Antigen; D008545:Melanoma / Q000276:immunology* / Q000378:metabolism; D014442:Monophenol Monooxygenase / Q000276:immunology / Q000378:metabolism; D009363:Neoplasm Proteins / Q000276:immunology; D010455:Peptides / Q000276:immunology* / Q000378:metabolism; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology* / Q000378:metabolism; D015854:Up-Regulation / Q000276:immunology
chemical_list: D000951:Antigens, Neoplasm; D018984:Epitopes, T-Lymphocyte; D015789:HLA-A2 Antigen; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D058965:MART-1 Antigen; C548667:MLANA protein, human; D009363:Neoplasm Proteins; D010455:Peptides; C052646:sarcoma glycoprotein gp96 rejection antigens; D007371:Interferon-gamma; D014442:Monophenol Monooxygenase