Esmon P C, Kuo H S, Fournel M A
Cutter Biological, Miles Inc, Berkeley, CA 94701.
Blood. 1990 Oct 15;76(8):1593-600.
The use of factor VIII prepared genetically engineered cell lines (rFVIII) may avoid some of the problems inherently associated with administering plasma-derived factor VIII (pdFVIII) concentrates to hemophilia A patients. Although rFVIII may represent an improvement over traditional therapeutics, the chance exists that protein production in cell culture may result in the presence of novel epitopes that may enhance the formation of inhibitor antibodies capable of neutralizing either rFVIII or pdFVIII. To assess the differences between rFVIII and its plasma-derived homologue, a rabbit immunogenicity model system was developed. Antibodies raised to rFVIII in rabbits were tested for the presence of antibodies capable of binding rFVIII but not pdFVIII, the presence of which would suggest that novel epitope(s) were present. This analysis was performed using a competitive enzyme-linked immunosorbent assay, as well as immunoadsorption. For either technique, rFVIII-specific antibodies were not detected, indicating that differences between rFVIII and pdFVIII were not found. When a rFVIII B-region deletion mutant was similarly tested, antibodies specific for this protein were found. These specific antibodies appeared to bind in the vicinity of the deletion site and their binding was not affected by carbohydrate removal. These results indicate that the rabbit immunogenicity model system is sensitive to alterations in the factor VIII molecule and suggest that full-length rFVIII will not be any more immunogenic in human patients than pdFVIII.
使用基因工程细胞系制备的凝血因子 VIII（重组凝血因子 VIII，rFVIII）或许可以避免向甲型血友病患者输注血浆源性凝血因子 VIII（pdFVIII）浓缩物时固有的一些问题。尽管 rFVIII 可能是对传统疗法的一种改进，但细胞培养中蛋白质的产生可能会导致出现新的表位，这些表位可能会增强能够中和 rFVIII 或 pdFVIII 的抑制性抗体的形成。为了评估 rFVIII 与其血浆源性同源物之间的差异，开发了一种兔免疫原性模型系统。检测在兔体内产生的针对 rFVIII 的抗体，看是否存在能够结合 rFVIII 但不能结合 pdFVIII 的抗体，若存在此类抗体，则表明存在新的表位。该分析使用了竞争性酶联免疫吸附测定法以及免疫吸附法。对于这两种技术，均未检测到 rFVIII 特异性抗体，这表明未发现 rFVIII 和 pdFVIII 之间存在差异。当对 rFVIII B 区缺失突变体进行类似检测时，发现了针对该蛋白的特异性抗体。这些特异性抗体似乎在缺失位点附近结合，并且它们的结合不受碳水化合物去除的影响。这些结果表明，兔免疫原性模型系统对凝血因子 VIII 分子的改变敏感，并表明全长 rFVIII 在人类患者中的免疫原性不会比 pdFVIII 更强。
