Transplant Research Center, Department of Surgery, Center for Transplantation Sciences, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.
Université de Paris, AP-HP, Hôpital Saint-Louis, Human Immunology, Pathophysiology and Immuntherapies, UMR976, INSERM, Paris, France.
Am J Transplant. 2021 Jul;21(7):2583-2589. doi: 10.1111/ajt.16591. Epub 2021 Apr 30.
Extracellular vesicles, including exosomes, are regularly released by allogeneic cells after transplantation. Recipient antigen-presenting cells (APCs) capture these vesicles and subsequently display donor MHC molecules on their surface. Recent evidence suggests that activation of alloreactive T cells by the so-called cross-dressed APCs plays an important role in initiating the alloresponse associated with allograft rejection. On the other hand, whether allogeneic exosomes can bind to T cells on their own and activate them remains unclear. In this study, we showed that allogeneic exosomes can bind to T cells but do not stimulate them in vitro unless they are cultured with APCs. On the other hand, allogeneic exosomes activate T cells in vivo and sensitize mice to alloantigens but only when delivered in an inflammatory environment.
细胞外囊泡，包括外泌体，在移植后会被同种异体细胞定期释放。受体抗原呈递细胞（APC）捕获这些囊泡，并随后在其表面上显示供体 MHC 分子。最近的证据表明，所谓的“交叉呈递”APC 激活同种反应性 T 细胞在启动与移植物排斥相关的同种反应中起着重要作用。另一方面，同种异体外泌体是否可以自行结合 T 细胞并激活它们尚不清楚。在这项研究中，我们表明，同种异体外泌体可以与 T 细胞结合，但除非与 APC 一起培养，否则不会刺激它们。另一方面，同种异体外泌体在体内激活 T 细胞并使小鼠对同种抗原敏感，但仅在递送至炎症环境中时才会发生这种情况。
