单链抗体对重症肌无力致病性抗乙酰胆碱受体抗体的抑制

Inhibition of pathogenic antibodies to the binding of acetylcholine receptor by a single chain variable fragment in myasthenia gravis

目的 探讨单链抗体 (ScFv)在体外对重症肌无力 (MG)的治疗作用。方法 从分离自MG患者胸腺的抗乙酰胆碱受体 (AChR)抗体构建单链抗体ScFv6 37,应用免疫荧光法、竞争性ELISA和竞争性放射免疫测定法 ,对ScFv6 37与人肌肉冰冻切片中AChR结合活性以及抑制致病性抗AChR抗体和MG患者血清与人AChR结合活性进行测定。结果 ScFv6 37能与人肌肉中神经肌肉接头处的AChR结合 ,对致病性抗AChR抗体与人AChR结合的抑制率可达 73 0 % ,对MG患者血清与人AChR结合的抑制率为 2 7 8%～ 4 5 5 %。结论 单链抗体在体外能抑制致病性抗AChR抗体与AChR的结合 ,对AChR具有保护作用。

Objective To investigate in vitro the therapeutic effects of single chain variable fragment (ScFv) on myasthenia gravis (MG).Methods ScFv637 was constructed from antigen binding fragment Fab637,an anti-acetylcholine receptor (AChR) antibody,derived from thymus of a patient with MG,and expressed in E coli . The specific binding activity of ScFv637 to AChR in neuromuscular junction of cryosections of human muscle was determined by using immunofluorescence technique,and the AChR in endplate was colocalized with rhodamine-labeled α-bungarotoxin. The inhibitive effects of ScFv637 on the binding of a pathogenic anti-AChR monoclonal antibody mAb35 and on the binding of sera of MG patients were measured by competitive ELISA and radioimmunoassay respectively.Results ScFv637 was able to bind to the fixed AChR in human muscle,and could also inhibit the binding of the pathogenic anti-AChR monoclonal antibody mAb35 and sera of MG patients to human AChR up to 73.0% and from 27.8% to 45.5% respectively.Conclusion ScFv has in vitro a protective effect on human AChR from binding of the pathogenic anti-AChR antibodies to AChR.