Thomas S, Turner M L, Williamson L M
NHS Blood and Transplant, Oak House, Reeds Crescent, Watford, WD24 4QN, England, United Kingdom.
Transfus Clin Biol. 2013 Sep;20(4):405-11. doi: 10.1016/j.tracli.2013.05.002. Epub 2013 Aug 6.
Three cases of vCJD transmission by blood transfusion have been reported in the UK, and a fourth case discovered at post-mortem. Modelling has been conducted to predict the number of cases that may occur in the future through transfusion, based on estimates of prevalence, infectivity and susceptibility, and a number of steps have been taken to reduce the risk of transmission. These include deferral of previously transfused donors, leucocyte depletion of all components, importation of plasma for certain patient groups and for fractionation, and the collection of the majority of platelets from single donors (by apheresis). However, even with these interventions, some future cases are still predicted. The UK-wide Advisory Committee on the Safety of Blood, Tissues and Organs (SaBTO) considers the evidence for clinical and cost-effectiveness of any proposed intervention, such as prion assays and filters, and makes recommendations to the governments of the UK. The development of prion assays is challenging as prions do not generate an immune response, do not have nucleic acid and are present in blood in very low concentrations against a high background of normal prion protein. It is critically important that prion assays show high levels of sensitivity and - especially -specificity for a healthy blood donor population. Assessment is impacted by the very short supply of positive human samples, necessitating the use of animal models. Filters that are capable of removing prions from blood components have been developed and CE marked, but it is again necessary to use animal models to study their efficacy. Guidelines have been produced for the assessment of the quality of red cells filtered through these devices, and a clinical safety study has recently been completed. In conclusion, the evaluation of screening assays and prion filters is challenging, time-consuming and costly, but these evaluations are critical to policy making.
英国已报告3例通过输血传播变异克雅氏病（vCJD）的病例，还有1例在尸检时被发现。已进行建模，根据患病率、传染性和易感性估计，预测未来可能通过输血出现的病例数，并已采取多项措施降低传播风险。这些措施包括推迟曾接受过输血的献血者献血、对所有血液成分进行白细胞去除、为某些患者群体和血液制品生产进口血浆，以及从单采献血者（通过血液成分单采术）采集大部分血小板。然而，即便采取了这些干预措施，仍预测会出现一些未来病例。全英国血液、组织和器官安全咨询委员会（SaBTO）会考量任何拟议干预措施（如朊病毒检测和过滤器）的临床和成本效益证据，并向英国政府提出建议。朊病毒检测的开发具有挑战性，因为朊病毒不会引发免疫反应，没有核酸，且在血液中的浓度极低，而正常朊病毒蛋白的背景浓度却很高。对于健康献血者群体而言，朊病毒检测具有高灵敏度，尤其是高特异性至关重要。由于阳性人类样本供应极为短缺，必须使用动物模型，这影响了评估工作。已开发出能够从血液成分中去除朊病毒的过滤器，并获得了CE认证，但同样有必要使用动物模型来研究其功效。已制定了评估通过这些设备过滤的红细胞质量的指南，并且一项临床安全性研究最近已经完成。总之，筛查检测和朊病毒过滤器的评估具有挑战性、耗时且成本高昂，但这些评估对政策制定至关重要。
