Fine epitope mapping of B cell response in patients with hemophilia A: Pilot

描述(由申请人提供)：使用FVIII因子(FVIII)治疗的严重血友病患者中有30%会产生抗FVIII抗体(抑制剂)。这是血友病A患者治疗中最严重的并发症，导致发病率和治疗费用的增加。这些产生的抗体可以抑制FVIII的生物活性。FVIII有5个结构域具有已知的功能意义，抗体大多针对FVIII的A2和C2结构域。然而，我们最近已经表明，FVIII的C2结构域内的表位具有独特的特征。在获得性血友病血浆和具有非常高滴度的非经典抑制物对FVIII有反应的获得性血友病血浆中，C2区域内的特异性表位(经典与非经典)比抑制物滴度更重要。中环 这个试点项目的假设是描述血友病A抑制剂患者血浆中代表的B细胞表位的谱，为统计分析提供数据，以设计一项前瞻性临床试验，比较表位谱和对FVIII治疗和免疫耐受治疗的结果的反应。我们建议使用一组鼠抗FVIII单抗将患者的多克隆血浆映射到特定的B细胞表位，以对抗FVIII的所有结构域，除了B结构域。我们将在多个体外凝血试验中比较表位谱与基因型以及对FVIII治疗的反应。在一组患者中，我们将有两个来自不同时间点的样本，我们将比较不同时间点表位光谱的变化和对FVIII的反应。

DESCRIPTION (provided by applicant): Thirty percent of patients with severe hemophilia treated with factor fVIII (fVIII) develop anti-fVIII antibodies (inhibitors). This is the most significant complication in the management of patients with hemophilia A leading to increases in morbidity as well as cost of treatment. These antibodies that develop can inhibit the biological activity of fVIII. There are 5 domains of fVIII that have known functional significance with antibodies most often being directed against the A2 and C2 domains of fVIII. However, we have recently shown that epitopes within the C2 doman of fVIII have unique characteristics. The specific epitope (classical vs. nonclassical) within the C2 domain was more important than inhibitor titer in response to fVIII in acquired hemophilia plasma and a murine monoclonal antibody (MAb) system with very high titer nonclassical inhibitors responding to fVIII. The central hypothesis of this pilot project is to describe the spectrum of B-cell epitopes that are represented in hemophilia A inhibitor patient plasmas to provide data for statistical analysis to design a prospective clinical trial comparing epitope spectrum and response to treatment with fVIII and to results of immune tolerance therapy. We propose to map the patient polyclonal plasma to specific B-cell epitopes using a panel of murine anit-fVIII monoclonal antibodies to all domains of fVIII except the B domain. We will compare the epitope spectrum to genotype as well response to treatment with fVIII in multiple in vitro coagulation assays. In a subset of patients we will have two samples from different points in time and we will compare the change of epitope spectrum and response to fVIII at the different time points.