Bakács T, Tusnády G, Végh Z, Merry A H, Kertész Z, Klein E
Department of Immunology, National Institute of Oncology, Budapest, Hungary.
Immunol Lett. 1993 Mar;35(3):213-7. doi: 10.1016/0165-2478(93)90185-5.
Lysis of group A and B erythrocytes by human complement was studied by an anti-A (BRIC.131) and an anti-B (BRIC.30) IgM monoclonal antibody in a 51Cr-release assay. The relative concentration of membrane-bound immunoglobulins was detected by flow cytometric analysis, and the amount of C1q and C3 bound to the sensitized red cells was measured by using purified, 125I-labelled molecules. The direct haemolysis was identical with both reagents in the presence of excess and suboptimal complement over a wide range of antibody concentration (between 50 and 7000 ng/ml). The indirect effect of membrane-bound antibody, i.e. its influence on complement binding by sensitized bystander cells, was examined in a cold target competition assay in which sensitized, non-labelled cells are present when complement is incubated with sensitized labelled cells. We have found that the competitive capacity of sensitized erythrocytes correlated with the amount of membrane-bound immunoglobulins. In accordance with our earlier findings, an equal level of target and competitor cell lysis was obtained only if the fluid phase anti-B antibody concentration was 2 to 4 times higher than that of the anti-A antibodies. We demonstrate in this paper that the different competitive activity of IgM anti-A and anti-B monoclonal antibodies might be accounted for by differences in their C1q and C3 binding capacities.
在一项⁵¹Cr释放试验中，通过抗A（BRIC.131）和抗B（BRIC.30）IgM单克隆抗体研究了人补体对A组和B组红细胞的溶解作用。通过流式细胞术分析检测膜结合免疫球蛋白的相对浓度，并使用纯化的¹²⁵I标记分子测量与致敏红细胞结合的C1q和C3的量。在广泛的抗体浓度范围（50至7000 ng/ml）内，在补体过量和亚最佳的情况下，两种试剂的直接溶血作用相同。在冷靶竞争试验中检测了膜结合抗体的间接作用，即在补体与致敏标记细胞孵育时存在致敏的未标记细胞的情况下，观察其对致敏旁观者细胞补体结合的影响。我们发现致敏红细胞的竞争能力与膜结合免疫球蛋白的量相关。根据我们早期的研究结果，只有当液相抗B抗体浓度比抗A抗体浓度高2至4倍时，才能获得相同水平的靶细胞和竞争细胞溶解。我们在本文中证明，IgM抗A和抗B单克隆抗体不同的竞争活性可能是由于它们C1q和C3结合能力的差异所致。
