Hultin M B, London F S, Shapiro S S, Yount W J
Blood. 1977 May;49(5):807-17.
Previous studies using immunoneutralization techniques have shown that many factor VIII inhibitors are IgG antibodies of a single light chain type. We have investigated this apparent homogeneity by immunoneutralization assay and liquid isoelectric focusing of inhibitor fractions from five hemophiliacs and two nonhemophiliacs. By immunoneutralization assay, inhibitors from four hemophiliacs and one nonhemophiliac were exclusively k light chain type: the fifth hemophilic inhibitor was predominantly k1 and the second nonhemophilic inhibitor was a mixture of k and gamma. However, heavy chain subtyping of the six predominantly or exclusively k inhibitors showed all to be mixtures of IgG4 and IgG1. By isoelectric focusing, two inhibitors showed multiple peaks of activity between pH 5 and 9. The remaining five showed predominant peaks of activity, which were solely IgGk1 between pH 5.8 and 7, with smaller peaks between pH 7 and 9. The most acidic major peak, focusing at pH 6, was IgG4 in the three cases tested. Two of these acidic peaks neutralized factor VIII more efficiently than other peaks in the same focusing profiles, suggesting greater affinity for factor VIII. These studies demonstrate that factor VIII inhibitors are composed of heterogenous subpopulations of immunoglobulins which can be separated by isoelectric focusing.
以往利用免疫中和技术开展的研究表明，许多凝血因子VIII抑制剂是单轻链类型的IgG抗体。我们通过免疫中和试验以及对来自五名血友病患者和两名非血友病患者的抑制剂组分进行液相等电聚焦，对这种明显的同质性进行了研究。通过免疫中和试验，来自四名血友病患者和一名非血友病患者的抑制剂均为纯κ轻链类型：第五名血友病患者的抑制剂主要为κ1，第二名非血友病患者的抑制剂是κ和γ的混合物。然而，对六种主要为或全部为κ的抑制剂进行重链亚型分析显示，它们均为IgG4和IgG1的混合物。通过等电聚焦，两种抑制剂在pH 5至9之间呈现多个活性峰。其余五种呈现主要活性峰，在pH 5.8至7之间仅为IgGκ1，在pH 7至9之间有较小的峰。在所检测的三例中，聚焦于pH 6的最酸性主峰为IgG4。在相同的聚焦图谱中，其中两个酸性峰比其他峰更有效地中和凝血因子VIII，表明对凝血因子VIII的亲和力更高。这些研究表明，凝血因子VIII抑制剂由免疫球蛋白的异质亚群组成，可通过等电聚焦进行分离。
