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Altered homeostasis of CD4(+) memory T cells in allogeneic hematopoietic stem cell transplant recipients: Chronic graft-versus-host disease enhances T cell differentiation and exhausts central memory T cell pool

Department of Hematology and Oncology, Kyoto University, Kioto, Kyōto, Japan
Biology of Blood and Marrow Transplantation (Impact Factor: 3.35). 11/2007; 13(10):1176-84. DOI: 10.1016/j.bbmt.2007.06.009
Source: PubMed

ABSTRACT An increased risk of late infection is a serious complication after allogeneic hematopoietic stem cell transplantation (AHSCT), especially for recipients with defective CD4(+) T cell recovery. Although chronic graft-versus-host disease (cGVHD) negatively influences CD4(+) T cell reconstitution, the mechanisms leading to this defect are not well understood. We found that the proportion of CD27(-) CD4(+) T cells was remarkably increased in ASHCT recipients with cGVHD or with repetitive infectious episodes. Isolated CD27(-) CD4(+) T cells from ASHCT recipients had significantly shortened telomere length, displayed enhanced vulnerability to activation-induced cell death, and showed extremely reduced clonal diversity, when compared with CD27(-) CD4(+) T cells from healthy donors. Also, CD27(+) CD4(+) T cells from AHSCT recipients easily lost their expression of CD27 in response to antigen stimulation regardless of cGVHD status. Taken together, these data indicate that homeostasis of memory CD4(+) T cells from AHSCT recipients is altered, and that they easily transit into CD27(-) effector memory T cells. Increased in vivo T cell stimulation observed in recipients with cGVHD further promotes the transition to effector memory cells, a change that decreases the central memory CD4(+) T cell pool and consequently weakens the recipient's defense against persistently infecting pathogens.

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