Regulatory T cells: tolerance induction in solid organ transplantation

The concept of regulatory T cell (T-reg) therapy in transplantation is now a reality. Significant advances in science and technology have enabled us to isolate human T-regs, expand them to clinically relevant numbers and infuse them into human transplant recipients. With several Phase I/II trials under way investigating T-reg safety and efficacy it is now more crucial than ever to understand their complex biology. However, our journey is by no means complete; results from these trials will undoubtedly provoke both further knowledge and enquiry which, alongside evolving science, will continue to drive the optimization of T-reg therapy in the pursuit of transplantation tolerance. In this review we will summarize current knowledge of T-reg biology, explore novel technologies in the setting of T-reg immunotherapy and address key prerequisites surrounding the clinical application of T-regs in transplantation.