title: Human G-CSF-mobilized CD34-positive peripheral blood progenitor cells can stimulate allogeneic T-cell responses: implications for graft rejection in mismatched transplantation.
abstract: To investigate mechanisms of stem cell graft rejection we studied the allo-stimulatory potential of G-CSF mobilized peripheral blood progenitor cells (PBPC). CD34+ cells were purified (>95%) in a two-step procedure using immunoaffinity columns for CD34 selection and T-depletion. The capacity of CD34+ cells to stimulate allogeneic T-cell responses was compared with other cells from the same individual. CD34+ cells induced potent proliferative responses at stimulator:responder ratios of 1:20, but were approximately 50-fold less efficient compared to dendritic cells. Furthermore, CD34+ cells primed responses from partially matched allogeneic T cells in bulk cultures. Dual-colour flow cytometry showed that the co-stimulatory molecules B7.1, CD40 and ICAM-1 were absent on resting CD34-positive progenitor cells, but were induced during incubation with allogeneic lymphocytes due to a cytokine-mediated effect. Up-regulation of accessory molecules on CD34+ cells was reproduced by incubation with interferon-gamma or GM-CSF which enhanced the allo-stimulatory activity of CD34+ cells. Blocking studies with inhibitory antibodies suggested co-stimulatory functions for B7.2, ICAM-3, CD40 and LFA-3. CD34+ cells were more efficient in inducing allogeneic T-cell responses when compared to the unprocessed leukapheresis products. The reduced allo-stimulatory ability of G-CSF mobilized PBPC could be explained by the presence of CD3+ 4+ and CD3+ 8+ lymphocytes with suppressor activity. We conclude that current methods of stem cell selection for transplantation do not avoid allosensitization of the recipient and that further graft manipulation with add-back of lymphocytes or selection of subsets of CD34+ cells with reduced allo-stimulatory ability may reduce graft rejection.
authors.affiliation: Bone Marrow Transplant Unit, Hematology Branch, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA. frits.vanrhee@rmh.edu
authors.forename: F
authors.initials: F
authors.lastname: van Rhee
authors.forename: Y Z
authors.initials: YZ
authors.lastname: Jiang
authors.forename: F
authors.initials: F
authors.lastname: Vigue
authors.forename: M
authors.initials: M
authors.lastname: Kirby
authors.forename: D
authors.initials: D
authors.lastname: Mavroudis
authors.forename: N F
authors.initials: NF
authors.lastname: Hensel
authors.forename: V
authors.initials: V
authors.lastname: Agarwala
authors.forename: E
authors.initials: E
authors.lastname: Clave
authors.forename: R
authors.initials: R
authors.lastname: Childs
authors.forename: A
authors.initials: A
authors.lastname: Raptis
authors.forename: E
authors.initials: E
authors.lastname: Sloand
authors.forename: C
authors.initials: C
authors.lastname: Carter
authors.forename: E J
authors.initials: EJ
authors.lastname: Read
authors.forename: J
authors.initials: J
authors.lastname: Barrett
mesh_terms: D019138:Antibodies, Blocking / Q000276:immunology; D018952:Antigens, CD34 / Q000276:immunology*; D002455:Cell Division; D002999:Clone Cells; D006084:Graft Rejection / Q000276:immunology; D016179:Granulocyte Colony-Stimulating Factor / Q000627:therapeutic use*; D019650:Hematopoietic Stem Cell Mobilization / Q000379:methods*; D006650:Histocompatibility Testing; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D007371:Interferon-gamma / Q000494:pharmacology; D008213:Lymphocyte Activation; D013601:T-Lymphocytes / Q000276:immunology* / Q000473:pathology
chemical_list: D019138:Antibodies, Blocking; D018952:Antigens, CD34; D018799:Intercellular Adhesion Molecule-1; D016179:Granulocyte Colony-Stimulating Factor; D007371:Interferon-gamma