Mechanisms of Immunomodulation by anti-RBC antibodies

描述（由申请人提供）：慢性输注红细胞（rbc）对于治疗许多疾病状态是必不可少的。虽然血液与ABO和RhD抗原相匹配，但还有数百种额外的血型抗原可供输血接受者产生抗体反应。对于慢性输血，患者可能对足够多的临床意义上的红细胞抗原产生免疫，基本上所有可用的红细胞单位都是不相容的。这要求要么放弃输血的有益和/或挽救生命的作用，要么输“最不相容”的血液，冒着可能致命的溶血性输血反应的风险。因此，对于一系列需要长期输血的疾病，对多种红细胞抗原的同种免疫可以阻止使用挽救生命的输血，导致相当大的发病率和/或死亡率。虽然使用抗d免疫球蛋白（RhIg）在防止RhD-母亲对胎儿RhD+红细胞的异体免疫方面取得了很高的成功，但在防止RhD-受体输注RhD+红细胞的异体免疫方面也有相当大的功效。不幸的是，没有类似于rhigg的产品可用于对抗其他血型抗原（如Kell， Kidd， Duffy等）。将rhigg样疗法扩展到这些抗原将是预防需要慢性红细胞输血治疗的患者的同种异体免疫的重要一步。这类试剂的开发需要对RhIg功能的机理理解。然而，尽管几十年来证实了RhIg的功效，但其机制仍然未知。迄今为止，还没有动物模型的描述，将允许基于假设的方法来阐明RhIg功能的机制。我们之前已经成功地描述了两种小鼠红细胞输血同种免疫模型的产生。这些模型是用在红细胞上表达鸡蛋溶菌酶（mHEL）或糖蛋白A （hGPA）的转基因小鼠产生的。通过将转基因红细胞输入野生型受体，可以研究对转基因红细胞抗原的同种免疫。在此，我们建议将该模型应用于RhIg功能的研究，从而深入阐明RhIg阻止对RBC抗原进行同种异体免疫的机制。中心假设：注射mHEL和/或hGPA抗体会阻止小鼠输注mHEL或hGPA红细胞的后续免疫，其生物学特性与预防人类rhg对RhD的同种免疫相似。特异性目的1：检测小鼠输注mHEL或hGPA红细胞后抗hel和抗hGPA的预防免疫能力。特异性目的2：确定分别向抗hel或抗gpa处理的小鼠输注mHEL或hGPA红细胞是否诱导对mHEL和hGPA抗原的免疫耐受。

DESCRIPTION (provided by applicant): Chronic transfusion of red blood cells (RBCs) is essential for treating many disease states. Although blood is matched for ABO and RhD antigens, there are several hundred additional blood group antigens against which transfusion recipients can mount antibody responses. With chronic transfusion, patients may become immunized to enough clinically significant RBC antigens that essentially all available RBC units are incompatible. This requires either forgoing the beneficial and/or life saving effects of transfusion or transfusing "least incompatible" blood and risking potentially fatal hemolytic transfusion reactions. Thus, for a range of illnesses requiring chronic transfusion, alloimmunization to multiple RBC antigens can preclude the use of life saving transfusions, resulting in considerable morbidity and/or mortality. Although the use of anti-D immunoglobulin (RhIg) is best known for its high success in preventing alloimmunization of RhD- mothers to fetal RhD+ RBCs, RhIg also has considerable efficacy in preventing alloimmunization to transfusion of RhD+ RBCs to RhD- recipients. Unfortunately, no RhIg-like products are available for use against other blood group antigens (i.e. Kell, Kidd, Duffy etc.). The extension of RhIg-like therapies to such antigens would be a significant step in preventing alloimmunization in patients requiring chronic RBC transfusion therapy. The development of such reagents requires a mechanistic understanding of RhIg function. However, despite decades of confirmed efficacy, the mechanisms of RhIg remain unknown. To date, no animal model of RhIg has been described that will allow a hypothesis based approach to elucidating the mechanisms of RhIg function. We have previously described the successful generation of two murine models of alloimmunization to RBC transfusion. These models were generated using transgenic mice expressing either hen egg lysozyme (mHEL) or glycophorin A (hGPA) on RBCs. By transfusing transgenic RBCs into wild-type recipients, alloimmunization to the transgenic RBC antigens can be studied. Herein, we propose to adapt this model to the study of RhIg function, allowing an in-depth elucidation of the mechanisms by which RhIg prevents alloimmunization to RBC antigens. Central Hypothesis: Injection of antibodies to mHEL and/or hGPA will prevent subsequent immunization in mice transfused with mHEL or hGPA RBCs, with similar biological characteristics to prevention of alloimmunization to RhD by RhIg in humans. Specific Aim 1: Test the ability of anti-HEL and anti-hGPA to prevent immunization in mice following transfusion of mHEL or hGPA RBC, respectively. Specific Aim 2: Determine if transfusion of mHEL or hGPA RBC into mice treated with anti-HEL or anti-GPA, respectively, induces immunological tolerance to mHEL and hGPA antigens. PUBLIC HEALTH RELEVANCE: Chronic transfusion of red blood cells (RBCs) is essential for treating many disease states. However, transfusion recipients can mount immune responses against donor RBCs. Over time, this can result in patients who cannot receive beneficial and/or life saving transfusions, because no compatible blood is available. There is a drug that can prevent this problem in limited settings, but it is not yet broadly applicable to RBC transfusion. Ultimately, the goal of this project is to extend this drug so that it can be used to prevent immune responses against RBCs from any donor. To do this, an animal model is required. We propose to generate an animal model, which will allow a mechanistic understanding of how the existing drug works, and how we can extend its benefits to RBCs of all types. Such a model has the potential to allow improvement of existing therapies and generation of new therapies, to facilitate transfusion as a treatment for any disease that requires transfusion. Some examples include: sickle cell anemia, alpha and beta thalassemia, aplastic anemia, renal failure, myeloproliferative disorders, bone marrow and solid organ transplantation, and other chronic anemias of various etiologies.