Center for Transplantation Sciences, Department of Surgery, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States.
Center for Transplantation Sciences, Department of Surgery, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States.
Cell Immunol. 2020 Mar;349:104063. doi: 10.1016/j.cellimm.2020.104063. Epub 2020 Feb 8.
Extracellular vesicles (EVs), including exosomes, ectosomes and apoptotic vesicles, play an essential role in communication between cells of the innate and adaptive immune systems. Recent studies showed that EVs released after transplantation of allogeneic tissues and organs are involved in the immune recognition and response leading to rejection or tolerance in mice. After skin, pancreatic islet, and solid organ transplantation, donor-derived EVs were shown to initiate direct inflammatory alloresponses by T cells leading to acute rejection. This occurred through presentation of intact allogeneic MHC molecules on recipient antigen presenting cells (MHC cross-dressing) and subsequent activation of T cells via semi-direct allorecognition. On the other hand, some studies have documented the role of EVs in maternal tolerance of fetal alloantigens during pregnancy and immune privilege associated with spontaneous tolerance of liver allografts in laboratory rodents. The precise nature of the EVs, which are involved in rejection or tolerance, and the cells which produce them, is still unclear. Nevertheless, several reports showed that EVs released in the blood and urine by allografts can be used as biomarkers of rejection. This article reviews current knowledge on the contribution of EVs in allorecognition by T cells and discusses some mechanisms underlying their influence on T cell alloimmunity in allograft rejection or tolerance.
细胞外囊泡（EVs），包括外泌体、ectosomes 和凋亡小体，在固有免疫和适应性免疫系统细胞之间的通讯中发挥着重要作用。最近的研究表明，同种异体组织和器官移植后释放的 EVs 参与了免疫识别和反应，导致小鼠排斥或耐受。在皮肤、胰岛和实体器官移植后，供体来源的 EVs 被证明通过 T 细胞引发直接炎症同种异体反应，导致急性排斥。这是通过在受者抗原呈递细胞上呈现完整的同种异体 MHC 分子（MHC 交叉染色），并通过半直接同种异体识别随后激活 T 细胞来实现的。另一方面，一些研究记录了 EVs 在怀孕期间母体对胎儿同种异体抗原的耐受以及与实验室啮齿动物肝脏同种异体移植自发耐受相关的免疫特权中的作用。参与排斥或耐受的 EVs 以及产生它们的细胞的确切性质仍不清楚。然而，有几项报道表明，同种异体移植物在血液和尿液中释放的 EVs 可用作排斥的生物标志物。本文综述了 EVs 在 T 细胞同种异体识别中的作用的最新知识，并讨论了它们对同种异体移植排斥或耐受中 T 细胞同种免疫的影响的一些机制。
