TRANSFUSION OF ANTIGENICALLY MODIFIED ERYTHROCYTES

红细胞(RBC)输注是人类免疫系统中的重要组成部分 治疗一批急、慢性医疗问题。在大多数 急性损伤，简单的RBC分型(ABO/Rh)足以识别 合适的捐赠者。然而，在以下方面经常遇到问题 接受慢性输血的个人，通常是少数群体(例如， 镰状细胞性贫血和地中海贫血)。事实上，简单的血型鉴定 通常不足以确定正确的匹配，因为这些 个体对微小的红细胞抗原产生输血反应。这 对较小的RBC抗原的反应性可以使其几乎不可能 确定合适的献血者。因此，最好是 人工伪装细胞抗原决定簇以允许 异种供体红细胞的存活及预防同种异体致敏 发生的。到目前为止，这是不可能的。但是，以前的 研究表明，聚(乙烯)的共价键 乙二醇组分与蛋白质的结合既能延长体内循环，又能 防止/减少蛋白质的抗原性。同样，对 脂质体已经证明，聚乙二醇偶联脂质体在 该膜还能延长体内循环时间。基于这些 发现，这是这一提议的假设，共价 非免疫原性长链聚合物(例如，聚乙二醇或聚乙二醇乙二醇酯)的结合 衍生品)可以有效地掩盖完整的红细胞的抗原性 供者红细胞的决定因素，降低红细胞免疫原性，以及 减少/预防输血反应 供者和受者红细胞表型。因此，该计划的具体目标 这项提议是为了确定：1)哪种化合物能有效地遮盖红细胞 抗原性和检测分子量和几何形状 (线性与分支)的聚乙二醇/聚乙二醇衍生物影响细胞 免疫原性；2)结构、功能和代谢后果 用聚乙二醇/聚乙二醇衍生物对红细胞衍生化的影响；3) 红细胞衍生化对体外和体内存活的影响。如中所述 这项提案，使用这项技术的初步研究表明 衍生的人红细胞在形态上是正常的 显著降低：ABO/次要红细胞抗原性、免疫原性、 抗红细胞抗体的结合和吞噬作用。此外， 衍生的小鼠红细胞在体内表现出正常的存活。总而言之， 非免疫原性物质与完整红细胞的共价结合可能具有 具有重要的临床应用价值。这些包括但不限于 对人红细胞进行衍生化以允许患者输血 难以匹配，对少量RBC抗原同种异体致敏，可能 在患有严重自身免疫性溶血性疾病的个体中。

Red blood cell (RBC) transfusions are a crucial component in the treatment of a number of acute and chronic medical problems. In most acute injuries, simple RBC typing (ABO/Rh) is sufficient to identify appropriate donors. However, problems are frequently encountered in individuals, usually minorities, receiving chronic transfusions (e.g., sickle cell anemia and the thalassemias). Indeed, simple blood typing often becomes insufficient in determining a proper match as these individuals develop transfusion reactions to minor RBC antigens. This reactivity to minor RBC antigens can make it nearly impossible to identify appropriate blood donors. Thus, it would be desirable to artificially disguise cellular antigenic determinants to permit the survival of heterologous donor RBC and prevent allosensitization from occurring. To date this has not been possible. However, previous studies have demonstrated that the covalent linkage of poly(ethylene glycol) [PEG] to proteins both prolongs in vivo circulation and also prevents/diminishes protein antigenicity. Similarly, studies on liposomes have demonstrate that inclusion of PEG-conjugated lipids in the membrane also prolonged in vivo circulation. Based on these findings, it is the hypothesis of this proposal that the covalent binding of non-immunogenic, long chain polymers (e.g., PEG or PEG derivatives) to intact RBC can effectively mask the antigenic determinants on donor RBC, reduce RBC immunogenicity, and diminish/prevent transfusion reactions arising from disparity between donor and recipient RBC phenotypes. Therefore, the Specific Aims of this proposal are to determine: 1) which compounds effectively mask RBC antigenicity and examine how molecular weight and geometric shape (linear vs. branched) of PEG/PEG-derivatives affect cellular immunogenicity; 2) the structural, functional and metabolic consequences of RBC derivatization with PEG/PEG-derivatives; and 3) the effects of RBC-derivatization on in vitro and in vivo survival. As outlined within the proposal, preliminary studies using this technology demonstrates that derivatized human RBC are morphologically normal and exhibit significantly decreased: ABO/minor RBC antigenicity, immunogenicity, binding of anti-RBC antibodies and phagocytosis. Furthermore, derivatized mouse RBC exhibit normal in vivo survival. In sum, the covalent attachment of non-immunogenic materials to intact RBC may have significant clinical applications. These include, but are not limited to, derivatization of human RBC to permit transfusions in patients difficult to match, allosensitized to minor RBC antigens, and possibly in individuals with severe autoimmune hemolytic disease.