Myhre E B, Erntell M
Mol Immunol. 1985 Aug;22(8):879-85. doi: 10.1016/0161-5890(85)90073-2.
The immunoglobulin-binding capacity of a Peptococcus magnus strain was studied in a sensitive binding assay using purified human immunoglobulin preparations. The P. magnus strain 312 was capable of binding 48% of polyclonal IgG. Twenty-four of 40 purified myeloma proteins (60%) representing immunoglobulin classes A, G and M showed definite reactivity with an uptake level ranging from 45 to 90%. The remaining 16 monoclonal proteins were non-reactive, binding less than 15%. One myeloma protein with antistaphylolysin and two with antistreptolysin O specificity, i.e. monoclonal proteins with defined antigen specificity, were highly reactive. Binding capacity was observed in all four IgG subclasses and in Ig classes A and M. Twenty-three of 27 myeloma proteins of kappa type were reactive but only one of 13 myeloma proteins of lambda type interacted with the P. magnus strain. Isotope-labelled Fab gamma, F(ab')2 gamma and F(ab')2 alpha fragments were effectively bound by the strain. IgG Fc fragments were completely non-reactive. Isolated light immunoglobulin chains inhibited in a dose-dependent way the uptake of intact IgG to bacteria. Purified heavy chains were non-inhibitory. Isotope-labelled antistaphylolysin IgG F(ab')2 fragments preincubated with staphylolysin were as reactive as free antibody fragments, suggesting that the bacterial binding structure is located outside the antibody-combining site. The immunoglobulin reactivity of P. magnus was not affected by heating the bacteria to 80 degrees C for 5 min nor by treatment with trypsin or sodium metaperiodate. Digestion of 2 X 10(9) organisms with 100 micrograms of pepsin and papain reduced the binding by 58 and 90%, respectively. These data indicate that the binding of immunoglobulin to P. magnus is a non-immune reactivity mediated by a heat-stable surface protein interacting with specific sites on the light chain of the immunoglobulin molecule.
利用纯化的人免疫球蛋白制剂，通过灵敏的结合试验研究了巨大消化球菌菌株的免疫球蛋白结合能力。巨大消化球菌菌株312能够结合48%的多克隆IgG。代表免疫球蛋白A、G和M类的40种纯化骨髓瘤蛋白中有24种（60%）表现出明确的反应性，摄取水平在45%至90%之间。其余16种单克隆蛋白无反应性，结合率低于15%。一种具有抗葡萄球菌溶血素的骨髓瘤蛋白和两种具有抗链球菌溶血素O特异性的骨髓瘤蛋白，即具有明确抗原特异性的单克隆蛋白，具有高度反应性。在所有四种IgG亚类以及IgA和IgM类中均观察到结合能力。27种κ型骨髓瘤蛋白中有23种具有反应性，但13种λ型骨髓瘤蛋白中只有一种与巨大消化球菌菌株相互作用。该菌株能有效结合同位素标记的Fabγ、F(ab')2γ和F(ab')2α片段。IgG Fc片段完全无反应性。分离的轻免疫球蛋白链以剂量依赖的方式抑制完整IgG对细菌的摄取。纯化的重链无抑制作用。与葡萄球菌溶血素预孵育的同位素标记抗葡萄球菌溶血素IgG F(ab')2片段与游离抗体片段一样具有反应性，这表明细菌结合结构位于抗体结合位点之外。将细菌加热至80℃ 5分钟，或用胰蛋白酶或偏高碘酸钠处理，均不影响巨大消化球菌的免疫球蛋白反应性。用100微克胃蛋白酶和木瓜蛋白酶消化2×10⁹个生物体，结合率分别降低了58%和90%。这些数据表明，免疫球蛋白与巨大消化球菌的结合是一种非免疫反应，由一种热稳定的表面蛋白介导，该蛋白与免疫球蛋白分子轻链上的特定位点相互作用。
