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Blood, 1 December 2008, Vol. 112, No. 12, pp. 4755-4764. Prepublished online as a Blood First Edition Paper on September 24, 2008; DOI 10.1182/blood-2008-02-142737.
TRANSPLANTATION Rapidly proliferating CD44hi peripheral T cells undergo apoptosis and delay posttransplantation T-cell reconstitution after allogeneic bone marrow transplantation1 Department of Medicine and Immunology, Memorial Sloan-Kettering Cancer Center, New York, NY; 2 Department of Medicine, Yale University School of Medicine, New Haven, CT; 3 Department of Medicine, Cancer Institute of New Jersey, New Brunswick; and 4 Department of Pathology, Albert Einstein College of Medicine, Bronx, NY
Delayed T-cell recovery is an important complication of allogeneic bone marrow transplantation (BMT). We demonstrate in murine models that donor BM-derived T cells display increased apoptosis in recipients of allogeneic BMT with or without GVHD. Although this apoptosis was associated with a loss of Bcl-2 and Bcl-XL expression, allogeneic recipients of donor BM deficient in Fas-, tumor necrosis factor–related apoptosis-inducing ligand (TRAIL)- or Bax-, or BM-overexpressing Bcl-2 or Akt showed no decrease in apoptosis of peripheral donor-derived T cells. CD44 expression was associated with an increased percentage of BM-derived apoptotic CD4+ and CD8+ T cells. Transplantation of RAG-2-eGFP–transgenic BM revealed that proliferating eGFPloCD44hi donor BM-derived mature T cells were more likely to undergo to apoptosis than nondivided eGFPhiCD44lo recent thymic emigrants in the periphery. Finally, experiments using carboxyfluorescein succinimidyl ester–labeled T cells adoptively transferred into irradiated syngeneic hosts revealed that rapid spontaneous proliferation (as opposed to slow homeostatic proliferation) and acquisition of a CD44hi phenotype was associated with increased apoptosis in T cells. We conclude that apoptosis of newly generated donor-derived peripheral T cells after an allogeneic BMT contributes to delayed T-cell reconstitution and is associated with CD44 expression and rapid spontaneous proliferation by donor BM-derived T cells.
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