American Journal of Transplantation: Volume 19, Number 1, January 2019

On the cover: Once considered “the enemy” of transplanted organs, T cells are now known to have both salutary and detrimental phenotypes, with T regulatory cells (T regs ) emerging as the most studied cell type thought to protect organs from immune rejection. In this issue, we feature several Original Articles addressing T regs biology. Wedel et al ( page 77) provide new insights into how T regs are activated to provide their immune‐mollifying effects. Baroja‐Mazo et al ( page 48) demonstrate how extracellular adenosine release during times of ischemia or stress can counter the beneficial effects of T regs , and in doing so, promote allograft rejection. Hoeppli et al ( page 62) address how T regs traffic to sites of inflammation to limit the detrimental spread of inflammation beyond that needed to control local threats. Finally, Christian LeGuern and Sharon Germana provide a Comprehensive Review ( page 15) on T reg specificity that informs the generation of custom T regs for use as cellular therapeutics. Cover design by Megan Llewellyn, Duke University Department of Surgery .