title: Heat shock protein 70/peptide complexes: potent mediators for the generation of antiviral T cells particularly with regard to low precursor frequencies.
abstract: BACKGROUND
  Heat shock protein 70 (HSP70) has gained major attention as an adjuvant capable of inducing antigen-specific CD8(+) and CD4(+) T-cell responses. The ability of HSP70/peptide complexes to elicit cytotoxic T-cell (CTL) responses by cross-presentation of exogenous antigens via HLA class I molecules is of central interest in immunotherapy. We examined the role of HSP70/CMVpp65(495-503)-peptide complex (HSP70/CMV-PC) in HLA class I-restricted cross-presentation for ex vivo expansion of CMV-specific CTLs.
  
  
  METHODS
  CMV-specific T cells generated from PBMCs of HLA-A*02:01/CMV-seropositive donors were stimulated for 21 days with HSP70/CMV-PC and analyzed in functional assays. As a control PBMCs were cultured in the presence of CMVpp65(495-503) peptide or HSP70. Increase of CMV-specific CTLs was visualized by pentameric HLA-A*02:01/CMVpp65(495-503) complex.
  
  
  RESULTS
  About 90% of HSP70/CMV-PC generated T cells were CMV-specific and exhibited significantly higher IFN-γ secretion, cytotoxic activity, and an increased heme oxygenase 1 (HO-1) gene expression as compared to about 69% of those stimulated with CMVpp65(495-503) peptide. We decided to classify the HLA-A*02:01/CMV-seropositive donors as weak, medium, and strong responder according to the frequency of generated A2/CMV-pentamer-positive CD8(+) T cells. HSP70/CMV-PC significantly induces strong antiviral T-cell responses especially in those donors with low memory precursor frequencies. Blockage of CD91 with α2-macroglobulin markedly reduced proliferation of antiviral T cells suggesting a major role of this receptor in the uptake of HSP70/CMV-PC.
  
  
  CONCLUSIONS
  This study clearly demonstrates that HSP70/CMV-PC is a potent mediator to induce stronger T-cell responses compared to antiviral peptides. This simple and efficient technique may help to generate significant quantities of antiviral CTLs by cross-presentation. Thus, we propose HSP70 for chaperoning peptides to reach an efficient level of cross-presentation. HSP70/peptide complexes may be particularly useful to generate stronger T-cell responses in cases of low precursor frequencies and may help to improve the efficiency of antigen-specific T-cell therapy for minor antigens.
authors: Institute for Transfusion Medicine, Hannover Medical School, Germany.
authors: Sabine
authors: S
authors: Tischer
authors: Megan
authors: M
authors: Basila
authors: Britta
authors: B
authors: Maecker-Kolhoff
authors: Stephan
authors: S
authors: Immenschuh
authors: Mathias
authors: M
authors: Oelke
authors: Rainer
authors: R
authors: Blasczyk
authors: Britta
authors: B
authors: Eiz-Vesper
mesh_terms: D000998:Antiviral Agents / Q000378:metabolism* / Q000494:pharmacology; D049109:Cell Proliferation / Q000187:drug effects; D003602:Cytotoxicity, Immunologic / Q000187:drug effects; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D053804:Granzymes / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D051547:Heme Oxygenase-1 / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism; D008213:Lymphocyte Activation / Q000187:drug effects; D010455:Peptides / Q000378:metabolism* / Q000494:pharmacology; D010750:Phosphoproteins / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013601:T-Lymphocytes / Q000166:cytology* / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D014763:Viral Matrix Proteins / Q000494:pharmacology; D000511:alpha-Macroglobulins / Q000378:metabolism
chemical_list: D000998:Antiviral Agents; D018840:HSP70 Heat-Shock Proteins; D010455:Peptides; D010750:Phosphoproteins; D012333:RNA, Messenger; D014763:Viral Matrix Proteins; D000511:alpha-Macroglobulins; C065418:cytomegalovirus matrix protein 65kDa; D007371:Interferon-gamma; D051547:Heme Oxygenase-1; D053804:Granzymes