Regulation of RBC Alloimmunization by Naturally Occurring and Adaptive Antibodies

红细胞输注是美国患者最常见的治疗方式， 大约每70个美国人中就有一个每年输血。一些长期输血的病人 对超过340种RBC同种抗原中的许多同种免疫，导致由于 缺乏足够的相容性红细胞单位。此外，红细胞同种抗体可导致溶血性疾病的 胎儿和新生儿。因此，RBC同种异体免疫的问题对于大量的人来说具有高度意义。 患者抗体传统上被认为是适应性免疫系统的一部分， 只有在接触抗原后才有反应;然而，近年来，一类新的预先存在的抗体 已经描述了在先天性和适应性之间的差距上架起桥梁的抗体（天然存在的抗体（nAb 免疫力大多数nAb是IgM（nIgM），其具有有限范围的特异性，包括自身抗原特异性。 受损组织的决定因素。输注的所有红细胞单位首先储存， 细胞损伤的特征模式，包括已知nIgM靶点的表达。在动物模型中，我们 已经报道了红细胞的储存增加了输血时的红细胞同种免疫，这一发现已经被 在一些后续的人类研究中观察到。在这种情况下，本申请将检验nIgM， 预先存在于未处理动物中，通过结合参与储存RBC的免疫原性增加 在储存的RBC的RBC表面上增加的保守基序，导致改变的抗原 呈递、T细胞活化和B细胞成熟。除nIgM外，RBC的正常适应性IgG 同种异体抗原可以在7-12天内检测到;然而，输注的红细胞继续循环至100- 100天。 人类120天（小鼠50天）。因此，适应性IgG可以在初次免疫期间结合循环RBC。 免疫应答，有可能影响正在进行的RBC同种免疫。事实上，我们提出了新的数据， 抗RBC IgG对正在进行的RBC同种免疫具有调节作用。在这方面，建议 研究还将检验适应性抗红细胞IgG通过穿梭 抗原呈递细胞的活化，以及 增强后续免疫力。在3个具体目标的背景下对这两个假设进行了研究： 具体目标1：确定nIgM在启动对RBC输注特异性的适应性同种免疫中的作用 目的2：抗RBC抗体改变适应性体液同种免疫的机制。具体目标3： 在人源化小鼠模型中测试抗RBC同种抗体对正在进行的RBC同种免疫的影响。 这些目标使用创新方法在细胞和分子水平上测试机械生物学， 并为将目标3转化为人类研究初步搭建桥梁。

RBC transfusion is the single most common therapeutic modality given to patients in America, with approximately 1 out of every 70 Americans being transfused each year. Some chronically transfused patients become alloimmunized against many of the over 340 RBC alloantigens, leading to morbidity and mortality due to lack of sufficient compatible RBC units. In addition, RBC alloantibodies can lead to hemolytic disease of the fetus and newborn. Thus, issues of RBC alloimmunization are of high significance to a large number of patients. Antibodies have traditionally been considered part of the adaptive immune system, which forms a response only after exposure to antigen; however, in recent years a new class of pre-existing antibodies (naturally occurring antibodies (nAbs)) have been described that bridge the gap between innate and adaptive immunity. Most nAbs are IgM (nIgMs) that have a limited range of specificities, including autoantigenic determinants on damaged tissues. All units of RBCs that are transfused are stored first, resulting in characteristic patterns of cell damage, including expression of known nIgMs targets. In animal models, we have reported that storage of RBCs increases RBC alloimmunization upon transfusion, a finding that has been observed in some follow up human studies. In this context, this applicaiton will test the hypothesis that nIgMs, pre-existing in naïve animals, are involved in increased immunogenicity of stored RBCs through binding conserved motifs that are increased on the RBC surface of stored RBCs, leading to altered antigen presentation, T cell activation and B cell maturation. In addition to nIgMs, normal adaptive IgG to RBC alloantigens can be detected as early as 7-12 days; however, transfused RBCs continue to circulate up to 100- 120 days in humans (50 days in mice). Thus adaptive IgGs can bind to circulating RBCs during a primary immune response, with the potential to affect ongoing RBC alloimmunization. Indeed, we present novel data that anti-RBC IgG, has regulatory effects upon ongoing RBC alloimmunization. In this context, the proposed studies will also test the hypothesis that adaptive anti-RBC IgGs affect ongoing alloimmunization by shuttling antigen to more immunogenic antigen-presenting cells, activation of the antigen-presenting cells, and increased subsequent immunity. These two hypotheses are investigated in the context of 3 specific aims: Specific aim 1: Determine the role of nIgM in initiating adaptive alloimmunity to RBC transfusion Specific aim 2: Mechanisms by which anti-RBC antibodies alter adaptive humoral alloimmunization. Specific aim 3: Test the effects of anti-RBC alloantibodies upon ongoing RBC alloimmunization in a humanized mouse model. These aims use innovative approaches to test mechanistic biology, at both the cellular and molecular level, and also generate an initial bridge to translation into human studies in aim 3.