INDUCTION OF TOLERANCE--FACTOR VIII IN HEMOPHILIC MICE

诱导耐受——血友病小鼠中的因子 VIII

• 批准号: 2758576
• 负责人: DOROTHEA H SCANDELLA
• 金额: $ 27.13万
• 依托单位: AMERICAN NATIONAL RED CROSS
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-09-30 至 2002-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2758576
• 关键词: CD28 molecule; CD40 molecule; T lymphocyte; active immunization; anamnestic reaction; antibody specificity; antigen presenting cell; blocking antibody; coagulation factor VIII; disease /disorder model; enzyme linked immunosorbent assay; gene therapy; hemophilia As; hybridomas; immune tolerance /unresponsiveness; immunoconjugates; immunoglobulin G; laboratory mouse; lymphocyte proliferation; monoclonal antibody; tissue /cell culture

Human antibodies that inactivate blood coagulation factor VIII fVIII inhibitors, develop in 25 percent of repeatedly transfused patients with severe hemophilia A and rarely in patients with moderate or mild hemophilia. Although the effects of inhibitors are variable, they often contribute to frequent, significant bleeding and disability, and they can present a life threatening complication. In addition, they are responsible for a large proportion of the cost of hemophilia care. The only effective method for inhibitor eradication is high dose fVIII therapy, which decreases inhibitor titers to undetectable levels in about 70 percent of patients, but it is very costly due to the frequent, high fVIII doses required. Patients with low inhibitor titers at the beginning of therapy are more rapidly and successfully tolerized, and tolerance is often long lived (up to 5 yrs.). It is not clear why 30 percent of patients are not tolerized and why it requires longer times in some patients. In 1995, hemophilia A mice were generated by targeted disruption of the murine fVIII gene in exons 16 or 17. We demonstrated that the mice respond to multiple fVIII intravenous injections of doses commonly used in humans by producing anti-fVIII antibodies. Moreover, others showed that splenic T cells from such mice can be stimulated by fVIII to proliferate in vitro. As human fVIII specific T and B cells are difficult to isolate from the peripheral blood, the hemophilic mice present a useful alternative for determining how immunological responses develop and how they can be eliminated. While the fVIII T and B cell epitopes may differ in humans and mice, the fundamental principles of immune recognition and tolerance should be similar. In this proposal we will use the hemophilic mice as a model to test high dose antigen stimulation for tolerance induction. We will determine if additional, simultaneous blocking of T and B cell costimulation by APCs with CTLA4Ig and T-B cell collaboration with anti-CD40L can further downregulate the immune response and whether this is more effective than using high antigen doses alone. Fusion of immunogenic polypeptides to IgG and expression in a retroviral vector introduced into bone marrow cells, leads to tolerance in both the primary and the secondary immune response. This method will also be tested in mice for tolerance induction to fVIII.

使血液凝血因子VIII FVIII失活的人类抗体 抑制剂，有25％的反复输血患者发育 严重的血友病A，很少有中度或轻度患者 血友病。 尽管抑制剂的影响是可变的，但它们经常 有助于频繁，大量的出血和残疾，他们 可以提出威胁生命的并发症。 另外，他们是 负责大部分血友病护理费用。 这 唯一有效消除抑制剂的方法是高剂量FVIII 治疗，将抑制剂滴度降低到无法检测到的水平 大约70％的患者，但由于频繁，这是非常昂贵的 需要高的FVIII剂量。 低抑制剂滴度的患者 治疗的开始更快，更成功地耐受性，并且 耐受性通常很长（最多5年）。 尚不清楚为什么30 患者的百分比不容忍，为什么需要更长的时间 在某些患者中。 1995年，靶向的血友病A小鼠产生 外显子16或17中鼠FVIII基因的破坏。我们证明了 小鼠对多种FVIII静脉注射剂量反应 通常通过产生抗FVIII抗体在人类中使用。而且， 其他人则表明，这种小鼠的脾脏T细胞可以通过 FVIII在体外增殖。 作为人FVIII特异性T和B细胞 很难与外周血分离，血友病小鼠 提出一个有用的替代方案，用于确定免疫学反应如何 发展以及如何消除它们。 而FVIII T和B细胞 人类和小鼠的表位可能有所不同，这是 免疫识别和耐受性应相似。在这个建议中，我们 将使用血友病小鼠作为测试高剂量抗原的模型 刺激耐受性诱导。 我们将确定是否额外 APC与CTLA4IG同时阻止T和B细胞共刺激 与抗CD40L的T-B细胞合作可以进一步下调 免疫反应以及这比使用高度更有效 仅抗原剂量。 免疫原性多肽与IgG融合 引入骨髓细胞的逆转录病毒载体中的表达， 导致初级和次级免疫的耐受性 回复。 该方法还将在小鼠中进行耐受性测试 对FVIII的归纳。