B-CELL RESPONSES TO CLOTTING FACTOR VIII

B 细胞对凝血因子 VIII 的反应

• 批准号: 7035899
• 负责人: Arthur Rumford Thompson
• 金额: $ 36.22万
• 依托单位: BLOODWORKS
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-05-01 至 2008-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7035899
• 关键词: B lymphocyte; Escherichia coli; T lymphocyte; affinity chromatography; autoantibody; cellular immunity; clinical research; coagulation factor VIII; crystallization; epitope mapping; family genetics; gene expression; hemophilia As; human subject; immune response; immune tolerance /unresponsiveness; immunoglobulin G; immunoglobulin isotypes; isoantibody; leukocyte activation /transformation; ligands; longitudinal human study; mutant; patient oriented research; protein binding; protein structure function

DESCRIPTION (provided by applicant): As a pathogenic B cell response, factor VIII inhibitors represent a major clinical challenge including alloantibodies in hemophilia A patients or autoantibodies in acquired hemophilia. Responses are polyclonal to a limited number of major epitopes on different domains and IgG4 responses often predominate. However, most studies to characterize factor VIII inhibitors have been on samples representing single points in time, focusing upon high titer antibodies at their peak response and defining fractions reacting with epitopes throughout entire domains. We propose to study fractions of the polyclonal responses that are directed to clusters of surface epitopes on factor VIIl's C domains to characterize variability between subjects and stability (or changes) across time in individual patients. We will study three sets of patient groups: (1) allo antibodies in severe hemophilia A, (2) auto antibodies in acquired hemophilia A and (3) combined auto and allo antibodies in patients with mild hemophilia A. C domain epitopes remain the most complex and least well understood. Affinity-purified antibody fractions binding to C domain epitope clusters will be characterized. We have expressed C2 and C1C2 and several mutants. Relative amounts of inhibiting and/or binding patient antibodies reacting to C2, its mutants or C1C2 will be assessed as will distribution of IgG isotypes, both between patients and longitudinally in a given patient's samples. Specific hemophilic C1C2 mutants will characterize responses in mildly severe patients with inhibitors. As a final component, we will define structural elements of C1C2's surface, and the extent of flexibility in conformations of residues on C2, surface residues that differ when the entire C domain is present. Results will provide insights into strategies for therapy of bleeding episodes and the induction of tolerance or prevention of alloimmunization.

描述（由申请方提供）：作为一种致病性B细胞应答，因子VIII抑制剂代表了主要的临床挑战，包括血友病A患者中的同种抗体或获得性血友病中的自身抗体。对不同结构域上有限数量的主要表位的反应是多克隆的，并且IgG 4反应通常占主导地位。然而，大多数表征因子VIII抑制剂的研究都是针对代表单个时间点的样本，重点关注峰值反应时的高滴度抗体，并定义与整个结构域中的表位反应的部分。我们建议研究针对因子VIII的C结构域上的表面表位簇的多克隆反应的分数，以表征个体患者中受试者之间的变异性和随时间的稳定性（或变化）。我们将研究三组患者组：（1）重度血友病A中的同种抗体，（2）获得性血友病A中的自身抗体和（3）轻度血友病A患者中的自身和同种抗体组合。C结构域表位仍然是最复杂和最不清楚的。将表征结合C结构域表位簇的亲和纯化的抗体级分。我们已经表达了C2和C1 C2以及几种突变体。将评估与C2、其突变体或C1 C2反应的抑制和/或结合患者抗体的相对量，以及IgG同种型在患者之间和给定患者样品中的纵向分布。特异性血友病C1 C2突变体将表征轻度重度抑制剂患者的反应。作为最后一个组成部分，我们将定义C1 C2的表面的结构元素，以及C2上的残基构象的灵活性程度，当整个C结构域存在时，表面残基不同。研究结果将为出血事件的治疗策略和诱导耐受或预防同种异体免疫提供见解。