Human G-CSF-mobilized CD34-positive peripheral blood progenitor cells can stimulate allogeneic T-cell responses: implications for graft rejection in mismatched transplantation.
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.
van Rhee
F
F
Bone Marrow Transplant Unit, Hematology Branch, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA. frits.vanrhee@rmh.edu
Jiang
Y Z
YZ
Vigue
F
F
Kirby
M
M
Mavroudis
D
D
Hensel
N F
NF
Agarwala
V
V
Clave
E
E
Childs
R
R
Raptis
A
A
Sloand
E
E
Carter
C
C
Read
E J
EJ
Barrett
J
J
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
D019138:Antibodies, Blocking; D018952:Antigens, CD34; D018799:Intercellular Adhesion Molecule-1; D016179:Granulocyte Colony-Stimulating Factor; D007371:Interferon-gamma