Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA.
Blood Cells Mol Dis. 2013 Jan;50(1):61-8. doi: 10.1016/j.bcmd.2012.08.009. Epub 2012 Sep 13.
During the last three decades, a growing body of clinical, basic science and animal model data has demonstrated that blood transfusions have important effects on the immune system. These effects include: dysregulation of inflammation and innate immunity leading to susceptibility to microbial infection, down-regulation of cellular (T and NK cell) host defenses against tumors, and enhanced B cell function that leads to alloimmunization to blood group, histocompatibility and other transfused antigens. Furthermore, transfusions alter the balance between hemostasis and thrombosis through inflammation, nitric oxide scavenging, altered rheologic properties of the blood, immune complex formation and, no doubt, several mechanisms not yet elucidated. The net effects are rarely beneficial to patients, unless they are in imminent danger of death due to exsanguination or life threatening anemia. These findings have led to appeals for more conservative transfusion practice, buttressed by randomized trials showing that patients do not benefit from aggressive transfusion practices. At the risk of hyperbole, one might suggest that if the 18th and 19th centuries were characterized by physicians unwittingly harming patients through venesection and bleeding, the 20th century was characterized by physicians unwittingly harming patients through current transfusion practices. In addition to the movement to more parsimonious use of blood transfusions, an effort has been made to reduce the toxic effects of blood transfusions through modifications such as leukoreduction and saline washing. More recently, there is early evidence that reducing the storage period of red cells transfused might be a strategy for minimizing adverse outcomes such as infection, thrombosis, organ failure and mortality in critically ill patients particularly at risk for these hypothesized effects. The present review will focus on two approaches, leukoreduction and saline washing, as means to reduce adverse transfusion outcomes.
在过去的三十年中，越来越多的临床、基础科学和动物模型数据表明，输血对免疫系统有重要影响。这些影响包括：炎症和先天免疫失调导致易受微生物感染；细胞（T 和自然杀伤细胞）宿主防御肿瘤的能力下降；以及增强 B 细胞功能，导致对血型、组织相容性和其他输注抗原的同种免疫。此外，输血通过炎症、一氧化氮清除、血液流变学特性改变、免疫复合物形成以及无疑还有几种尚未阐明的机制改变了止血和血栓形成之间的平衡。这些净效应对患者很少有益，除非他们因失血或危及生命的贫血而处于即将死亡的危险之中。这些发现促使人们呼吁采取更为保守的输血实践，并得到了随机试验的支持，这些试验表明，积极的输血实践并不能使患者受益。夸张一点说，人们可能会认为，如果 18 世纪和 19 世纪的医生通过静脉切开术和放血无意中伤害了患者，那么 20 世纪的医生则通过当前的输血实践无意中伤害了患者。除了努力更节约地使用血液制品外，还努力通过白细胞减少和盐水洗涤等方法减少输血的毒性作用。最近，有早期证据表明，减少输注红细胞的储存时间可能是一种策略，可以最大限度地减少感染、血栓形成、器官衰竭和死亡率等不良后果，特别是对那些有这些假设影响风险的危重病患者。本综述将重点关注两种方法，即白细胞减少和盐水洗涤，作为减少输血不良后果的手段。
