Shima M, Nakai H, Scandella D, Tanaka I, Sawamoto Y, Kamisue S, Morichika S, Murakami T, Yoshioka A
Department of Paediatrics, Nara Medical University, Kashihara City, Japan.
Br J Haematol. 1995 Nov;91(3):714-21. doi: 10.1111/j.1365-2141.1995.tb05374.x.
Factor VIII (FVIII) inhibitor alloantibodies obtained from seven severe haemophilia A patients were examined for their binding regions and their effects on FVIII binding to von Willebrand factor (vWF). Immunoblotting analysis with a panel of recombinant fragments demonstrated that the binding regions of antibodies in cases 1-5 were contained in the C2 domain of the light chain. Antibodies from cases 1 and 2, which recognized an epitope within residues 2248-2312, completely inhibited FVIII/vWF binding in an ELISA (IC50: 5.0 and 9.0 micrograms/ml, respectively). Antibodies from case 3 recognizing 2170-2312 and case 5 recognizing 2170-2327 also inhibited FVIII/vWF binding (IC50: 110 and 400 micrograms/ml, respectively). Case 4 antibodies recognizing 2218-2307 showed barely detectable inhibition and cases 6 and 7 antibodies recognizing the 44 kD heavy chain, did not inhibit. Our results demonstrate that all anti-C2 alloantibodies with epitopes that extend to the residue 2312 inhibit vWF binding and that an overlap of the inhibitor epitope with residues 2308-2312 is critical for maximal inhibition of vWF binding. Prevention of FVIII/vWF binding appears to be a common property of anti-C2 domain inhibitor alloantibodies.
对7例重度甲型血友病患者产生的凝血因子VIII（FVIII）抑制性同种抗体的结合区域及其对FVIII与血管性血友病因子（vWF）结合的影响进行了检测。用一组重组片段进行免疫印迹分析表明，病例1-5中抗体的结合区域位于轻链的C2结构域。病例1和2的抗体识别2248-2312位残基内的一个表位，在酶联免疫吸附测定（ELISA）中完全抑制FVIII/vWF结合（IC50分别为5.0和9.0微克/毫升）。病例3识别2170-2312的抗体和病例5识别2170-2327的抗体也抑制FVIII/vWF结合（IC50分别为110和400微克/毫升）。病例4识别2218-2307的抗体显示几乎检测不到抑制作用，病例6和7识别44kD重链的抗体则无抑制作用。我们的结果表明，所有表位延伸至2312位残基的抗C2同种抗体均抑制vWF结合，且抑制剂表位与2308-2312位残基的重叠对于最大程度抑制vWF结合至关重要。防止FVIII/vWF结合似乎是抗C2结构域抑制性同种抗体的一个共同特性。
