Division of Abdominal Transplant, Department of Surgery, Stanford University School of Medicine, Stanford, California, USA.
Curr Opin Organ Transplant. 2019 Feb;24(1):37-41. doi: 10.1097/MOT.0000000000000590.
Natural killer (NK) cells are effector cells of the innate immune system that can lyse target cells without prior sensitization and are important in host defense to virally infected and transformed cells. Although the concept of 'missing-self' would suggest NK cells could target foreign allografts, the prevailing dogma has been that NK cells are not active participants in the rejection of solid organ allografts. This review summarizes recent studies that challenge this conclusion and instead suggest NK cells are important in outcomes posttransplant.
NK cells expressing specific cell surface receptors may promote graft damage and rejection. However, recent studies suggest some NK cell subsets have tolerogenic or immunoregulatory potential and promote graft stability, suggesting a dichotomous role for NK cells after transplant. Furthermore, NK cells respond to cells infected with cytomegalovirus and Epstein-Barr virus, and studies suggest some NK cells have immune memory.
Our understanding of the role of NK cells posttransplant has evolved from 'no role' to the current idea that NK cells may have 'complex interactions' that impact graft outcomes. Additional studies, using cutting edge techniques to comprehensively analyze the phenotypic and functional subsets of NK cells in transplant recipients, are clearly necessary.
自然杀伤 (NK) 细胞是先天免疫系统的效应细胞，能够在无需预先致敏的情况下裂解靶细胞，在宿主防御病毒感染和转化细胞方面发挥重要作用。尽管“缺失自我”的概念表明 NK 细胞可以靶向异体移植物，但流行的观点一直认为 NK 细胞不是实体器官同种异体移植排斥反应的积极参与者。本综述总结了最近的研究，这些研究挑战了这一结论，反而表明 NK 细胞在移植后结果中很重要。
表达特定细胞表面受体的 NK 细胞可能促进移植物损伤和排斥。然而，最近的研究表明，一些 NK 细胞亚群具有耐受原性或免疫调节潜力，并促进移植物稳定，这表明 NK 细胞在移植后具有双重作用。此外，NK 细胞对巨细胞病毒和 Epstein-Barr 病毒感染的细胞作出反应，研究表明一些 NK 细胞具有免疫记忆。
我们对移植后 NK 细胞作用的理解已经从“无作用”发展到目前的观点，即 NK 细胞可能具有“复杂的相互作用”，影响移植物的结果。显然，需要使用先进的技术，对移植受者的 NK 细胞的表型和功能亚群进行全面分析，以开展更多的研究。
