title: Alloreactive and leukemia-reactive T cells are preferentially derived from naive precursors in healthy donors: implications for immunotherapy with memory T cells.
abstract: BACKGROUND
  HLA mismatch antigens are major targets of alloreactive T cells in HLA-incompatible stem-cell transplantation, which can trigger severe graft-versus-host disease and reduce survival in transplant recipients. Our objective was to identify T-cell subsets with reduced in vitro reactivity to allogeneic HLA antigens.
  
  
  METHODS
  We sorted CD4 and CD8 T-cell subsets from peripheral blood by flow cytometry according to their expression of naive and memory markers CD45RA, CD45RO, CD62L, and CCR7. Subsets were defined by a single marker to facilitate future establishment of a clinical-grade procedure for reducing alloreactive T-cell precursors and graft-versus-host disease. T cells were stimulated in mixed lymphocyte reactions against HLA-deficient K562 cells transfected with single HLA-A/-B/-C/-DR/-DQ mismatch alleles. Alloreactivity was measured by interferon-γ spot production and cell proliferation.
  
  
  RESULTS
  We observed that allogeneic HLA-reactivity was preferentially derived from subsets enriched for naïve T cells rather than memory T cells in healthy donors, irrespective of the HLA mismatch allele. This separation was most efficient if CD45RA (versus other markers) was used for sorting. The numbers of allogeneic HLA-reactive effector cells were in median 7.2-fold and 16.6-fold lower in CD45RA(neg) memory CD8 and CD4 T cells than in entire CD8 and CD4 T cells, respectively. In contrast, proliferation of memory T cells in response to allogeneic HLA was more variably reduced (CD8) or equivalent (CD4) when compared to that of naïve T cells. We also demonstrated in HLA-matched donor-patient pairs that leukemia-reactive CD8 cytotoxic T-lymphocytes were mainly derived from subsets enriched for naïve T cells compared to memory T cells.
  
  
  CONCLUSIONS
  Memory T-cell subsets of most healthy individuals showed decreased allogeneic HLA-reactivity, but lacked significant anti-leukemia responses in vitro. The clinical use of memory or naïve-depleted T cells might be beneficial for HLA-mismatched patients at high risk of graft-versus-host disease and low risk of leukemia relapse. Preferred allografts are those which contain leukemia-reactive memory T cells. Alternatively, replenishment with leukemia-reactive T cells isolated from naïve subsets is desirable.
authors.affiliation: 3rd Department of Medicine, University Medical Center of Johannes Gutenberg-University, Mainz, Germany.
authors.forename: Eva
authors.initials: E
authors.lastname: Distler
authors.forename: Andrea
authors.initials: A
authors.lastname: Bloetz
authors.forename: Jana
authors.initials: J
authors.lastname: Albrecht
authors.forename: Saliha
authors.initials: S
authors.lastname: Asdufan
authors.forename: Alexander
authors.initials: A
authors.lastname: Hohberger
authors.forename: Michaela
authors.initials: M
authors.lastname: Frey
authors.forename: Elke
authors.initials: E
authors.lastname: Schnürer
authors.forename: Simone
authors.initials: S
authors.lastname: Thomas
authors.forename: Matthias
authors.initials: M
authors.lastname: Theobald
authors.forename: Udo F
authors.initials: UF
authors.lastname: Hartwig
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Herr
mesh_terms: D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D045744:Cell Line, Tumor; D006086:Graft vs Host Disease / Q000276:immunology; D006680:HLA Antigens / Q000276:immunology; D006801:Humans; D007156:Immunologic Memory; D007167:Immunotherapy; D020014:K562 Cells; D007938:Leukemia / Q000276:immunology*; D054504:Precursor Cells, T-Lymphoid / Q000378:metabolism*; D054400:Receptors, CCR7 / Q000276:immunology / Q000378:metabolism; D013601:T-Lymphocytes / Q000276:immunology* / Q000637:transplantation*; D014019:Tissue Donors; D014184:Transplantation, Homologous
chemical_list: D006680:HLA Antigens; D054400:Receptors, CCR7