Vidal M A, Conde F P
J Immunol. 1985 Aug;135(2):1232-8.
The immunoglobulin site(s) that mediates the alternative mechanism of interaction between immunoglobulins and staphylococcal protein A (SpA) was studied by using a monoclonal human IgM. Several IgM fragments were tested for their inhibitory effect in a competitive binding assay of 125I-IgM to SpA. Only those fragments containing Fab mu pieces showed some inhibitory activity. The reactivity of the Fab mu region was retained in some of its subfragments, such as Fv or the VH domain, unlike isolated light chains or VL domains. Furthermore, antibodies specific for the VH domain completely inhibited the SpA-IgM interaction. These results indicate that the alternative SpA-binding site of IgM is located in VH regions.
利用单克隆人IgM研究了介导免疫球蛋白与葡萄球菌蛋白A（SpA）之间相互作用的替代机制的免疫球蛋白位点。在125I-IgM与SpA的竞争性结合试验中，测试了几种IgM片段的抑制作用。只有那些含有Fabμ片段的片段表现出一定的抑制活性。与分离的轻链或VL结构域不同，Fabμ区域的反应性在其一些亚片段中得以保留，如Fv或VH结构域。此外，针对VH结构域的特异性抗体完全抑制了SpA-IgM的相互作用。这些结果表明，IgM的替代SpA结合位点位于VH区域。
