Depletion‐Resistant CD4 T Cells Enhance Thymopoiesis During Lymphopenia |
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Authors: | K. Ayasoufi R. Fan A. Valujskikh |
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Affiliation: | 1. Department of Immunology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH;2. Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH |
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Abstract: | Lymphoablation is routinely used in transplantation, and its success is defined by the balance of pathogenic versus protective T cells within reconstituted repertoire. While homeostatic proliferation and thymopoiesis may both cause T cell recovery during lymphopenia, the relative contributions of these mechanisms remain unclear. The goal of this study was to investigate the role of the thymus during T cell reconstitution in adult allograft recipients subjected to lymphoablative induction therapy. Compared with euthymic mice, thymectomized heart allograft recipients demonstrated severely impaired CD4 and CD8 T cell recovery and prolonged heart allograft survival after lymphoablation with murine anti‐thymocyte globulin (mATG). The injection with agonistic anti‐CD40 mAb or thymus transplantation only partially restored T cell reconstitution in mATG‐treated thymectomized mice. After mATG depletion, residual CD4 T cells migrated into the thymus and enhanced thymopoiesis. Conversely, depletion of CD4 T cells before lymphoablation inhibited thymopoiesis at the stage of CD4?CD8?CD44hiCD25+ immature thymocytes. This is the first demonstration that the thymus and peripheral CD4 T cells cooperate to ensure optimal T cell reconstitution after lymphoablation. Targeting thymopoiesis through manipulating functions of depletion‐resistant helper T cells may thus improve therapeutic benefits and minimize the risks of lymphoablation in clinical settings. |
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Keywords: | basic (laboratory) research/science immunobiology immunosuppression/immune modulation Immunosuppressant polyclonal preparations: rabbit anti‐thymocyte globulin immunosuppressive regimens induction lymphocyte biology T cell biology thymus/thymic biology |
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