B-CELL RESPONSES TO CLOTTING FACTOR VIII

B 细胞对凝血因子 VIII 的反应

• 批准号: 6727405
• 负责人: Arthur Rumford Thompson
• 金额: $ 36.26万
• 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/6727405
• 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（由申请人提供）：作为一种致病性B细胞反应，因子VIII抑制剂代表了主要的临床挑战，包括血友病A患者的同种抗体或获得性血友病的自身抗体。反应是对不同域上有限数量的主要表位的多克隆，而IgG4反应通常占主导。然而，大多数表征VIII因子抑制剂的研究都在代表单个时间点的样品上，重点是高滴度抗体在其峰值响应时的高滴度抗体，并定义了与整个域的表位反应的分数。我们建议研究针对因子VIIL C域的表面表位簇的多克隆响应的分数，以表征单个患者的时间之间受试者和稳定性（或变化）之间的变异性。我们将研究三组​​患者组：（1）严重的血友病A中的同抗抗体，（2）在获得的血友病A中的自身抗体，以及（3）轻度血友病A的自动抗体和杂种抗体。将表征与C结构域表位簇结合的亲和纯化抗体分数。我们已经表达了C2和C1C2以及几个突变体。相对量的抑制和/或结合患者抗体对C2的反应，其突变体或C1C2将被评估，因为在给定患者的样本中，患者和纵向的IgG同种型将分布IgG同种型。特定的血友病C1C2突变体将表征有抑制剂的严重严重患者的反应。作为最终组成部分，我们将定义C1C2表面的结构元素，以及C2上残基构象的柔韧性，当存在整个C结构域时，表面残基有所不同。结果将提供有关治疗出血事件的策略以及诱导耐受性或预防同种异体免疫化的策略。