title: Successful generation of primary virus-specific and anti-tumor T-cell responses from the naive donor T-cell repertoire is determined by the balance between antigen-specific precursor T cells and regulatory T cells.
abstract: BACKGROUND
  One of the major challenges in allogeneic stem cell transplantation is to find a balance between the harmful induction of graft-versus-host disease and the beneficial graft-versus-leukemia and pathogen-specific immune responses. Adoptive transfer of in-vitro generated donor T cells with specific anti-leukemic or pathogen-specific activity may be effective. However, in many cases this requires the in-vitro priming and expansion of antigen-specific precursor T cells from the naïve donor T-cell repertoire.
  
  
  METHODS
  Antigen-specific CD8 T cells were generated by co-culture of CD45RO-depleted, regulatory T cell-depleted donor peripheral blood mononuclear cells with autologous peptide-loaded dendritic cells, followed by two re-stimulations with peptide-loaded autologous monocytes. Responding T cells were isolated based on CD137 expression and further purified using peptide/major histocompatibility complex tetramers.
  
  
  RESULTS
  Using this method we were able to reproducibly generate functionally high avidity T cells directed against multiple viral antigens and minor histocompatibility antigens from the naïve T-cell repertoire of seronegative, minor histocompatibility antigen-negative donors. Furthermore, we demonstrated that reduction of the regulatory T-cell frequency by depletion of CD45RO(+) responder cells resulted in improved priming and expansion of antigen-specific precursor T cells.
  
  
  CONCLUSIONS
  In conclusion, we present a robust method for the in-vitro induction and isolation of antigen-specific T cells from the naïve repertoire. We demonstrate that the likelihood of successful generation of primary immune responses is determined by a delicate balance between the numbers of antigen-specific precursor T cells and the numbers and activation state of regulatory T cells locally at the site of priming of the immune response.
authors.affiliation: Dept. of Hematology, Leiden University Medical Center, Leiden, The Netherlands. i.jedema@lumc.nl
authors.forename: Inge
authors.initials: I
authors.lastname: Jedema
authors.forename: Marian
authors.initials: M
authors.lastname: van de Meent
authors.forename: Jeanette
authors.initials: J
authors.lastname: Pots
authors.forename: Michel G D
authors.initials: MG
authors.lastname: Kester
authors.forename: Martha T
authors.initials: MT
authors.lastname: van der Beek
authors.forename: J H Frederik
authors.initials: JH
authors.lastname: Falkenburg
mesh_terms: D015703:Antigens, CD / Q000276:immunology / Q000378:metabolism; D000956:Antigens, Viral / Q000276:immunology*; D016207:Cytokines / Q000276:immunology / Q000494:pharmacology; D003587:Cytomegalovirus / Q000276:immunology; D000939:Epitopes / Q000276:immunology; D006086:Graft vs Host Disease / Q000276:immunology / Q000378:metabolism; D015234:HLA-A Antigens / Q000276:immunology; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000276:immunology; D008212:Lymphocyte Depletion; D009369:Neoplasms / Q000276:immunology; D054504:Precursor Cells, T-Lymphoid / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D050378:T-Lymphocytes, Regulatory / Q000276:immunology* / Q000378:metabolism; D014019:Tissue Donors; D014780:Viruses / Q000276:immunology
chemical_list: D015703:Antigens, CD; D000956:Antigens, Viral; D016207:Cytokines; D000939:Epitopes; D015234:HLA-A Antigens