title: T-cell reconstitution after unmanipulated, CD8-depleted or CD34-selected nonmyeloablative peripheral blood stem-cell transplantation.
abstract: BACKGROUND
  We have previously shown that CD8 depletion or CD34 selection of peripheral blood stem cells (PBSC) reduced the incidence of acute graft-versus-host disease (GvHD) after nonmyeloablative stem-cell transplantation (NMSCT). In this study, we analyze the effect of CD8 depletion or CD34 selection of the graft on early T-cell reconstitution.
  
  
  METHODS
  Nonmyeloablative conditioning regimen consisted in 2 Gy total-body irradiation (TBI) alone, 2 Gy TBI and fludarabine, or cyclophosphamide and fludarabine. Patients 1 to 18 received unmanipulated PBSC, patients 19 to 29 CD8-depleted PBSC, and patients 30 to 35 CD34-selected PBSC.
  
  
  RESULTS
  T-cell counts, and particularly CD4+ and CD4CD45RA+ counts, remained low the first 6 months after nonmyeloablative stem-cell transplantation (NMSCT) in all patients. CD34 selection (P<0.0001) but not CD8 depletion of PBSC significantly decreased T-cell chimerism. Donor T-cell count was similar in unmanipulated compared with CD8-depleted PBSC recipients but was significantly lower in CD34-selected PBSC recipients (P=0.0012). T cells of recipient origin remained stable over time in unmanipulated and CD8-depleted PBSC patients but expanded in some CD34-selected PBSC recipients between day 28 and 100 after transplant. Moreover, whereas CD8 depletion only decreased CD8+ counts (P<0.047), CD34 selection reduced CD3+(P<0.001), CD8+(P<0.016), CD4+ (P<0.001), and CD4+CD45RA+ (P<0.001) cell counts. T-cell repertoire was restricted in all patients on day 100 after hematopoietic stem-cell transplantation but was even more limited after CD34 selection (P=0.002).
  
  
  CONCLUSIONS
  Despite of the persistence of a significant number of T cells of recipient origin, T-cell counts were low the first 6 months after NMSCT. Moreover, contrary with CD8 depletion of the graft that only affects CD8+ lymphocyte counts, CD34 selection dramatically decreased both CD8 and CD4 counts.
authors.affiliation: Department of Medicine, Division of Hematology, University of Liège, CHU Sart-Tilman, 4000 Liège, Belgium.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Baron
authors.forename: Nicole
authors.initials: N
authors.lastname: Schaaf-Lafontaine
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Humblet-Baron
authors.forename: Nathalie
authors.initials: N
authors.lastname: Meuris
authors.forename: Emilie
authors.initials: E
authors.lastname: Castermans
authors.forename: Etienne
authors.initials: E
authors.lastname: Baudoux
authors.forename: Pascale
authors.initials: P
authors.lastname: Frère
authors.forename: Vincent
authors.initials: V
authors.lastname: Bours
authors.forename: Georges
authors.initials: G
authors.lastname: Fillet
authors.forename: Yves
authors.initials: Y
authors.lastname: Beguin
mesh_terms: D000328:Adult; D000368:Aged; D015703:Antigens, CD / Q000097:blood; D018952:Antigens, CD34 / Q000097:blood*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D005260:Female; D005500:Follow-Up Studies; D006650:Histocompatibility Testing; D006801:Humans; D007694:Killer Cells, Natural / Q000276:immunology; D018655:Lymphocyte Count; D008212:Lymphocyte Depletion / Q000592:standards*; D008297:Male; D008875:Middle Aged; D009190:Myelodysplastic Syndromes / Q000628:therapy; D009369:Neoplasms / Q000145:classification / Q000628:therapy; D033581:Stem Cell Transplantation / Q000379:methods*; D013601:T-Lymphocytes / Q000276:immunology*; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D015703:Antigens, CD; D018952:Antigens, CD34