Immune system regulation is of paramount importance to host survival. In settings of autoimmunity and alloimmunity, control is lost, resulting in injury to vital organs and tissues. Naturally occurring, thymic-derived T regulatory (Treg) cells that express CD4, CD25, and the forkhead box protein 3 (FoxP3) are potent suppressors of these adverse immune responses. Preclinical studies have shown that either freshly isolated or ex vivo expanded Treg cells can prevent both local and systemic organ and tissue destruction. Although promising, human Treg cell infusion therapy has heretofore been difficult to implement in the clinic, and relatively few clinical trials have been initiated. This review will focus on the preclinical models that provide the rationale for current trials and it will address both the challenges and opportunities in human Treg cell therapy.
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We thank R. Carroll and K. Hippen for careful proofreading and helpful suggestions and members of the JDRF Collaborative Centers for Cell Therapy and the JDRF Center on Cord Blood Therapies for Type 1 Diabetes for insightful discussions. Work in our laboratories was supported by JDRF, a sponsored research grant from Becton and Dickinson & Company, R01CA105216, R01AI057838, R37HL56067, P01CA670493, and a translational grant (# 6220) from the Leukemia and Lymphoma Society. The authors declare a potential conflict of interest in the content of the manuscript because of the prior receipt of licensing fees and research support from BD Biosciences.