Krieger G, Kneba M, Bolz I, Nagel G A
Department of Internal Medicine, University Göttingen, Federal Republic of Germany.
Clin Immunol Immunopathol. 1988 Jan;46(1):14-23. doi: 10.1016/0090-1229(88)90002-5.
The aim of the present study was to isolate and characterize immune complexes measured by the 125I-C1q binding assay in breast cancer sera. The C1q binding assay detects immune complexes by their binding to 125I-C1q and subsequent precipitation with PEG. We purified the C1q binding material from these precipitates by superose 6 gel filtration and cation exchange chromatography. The isolation steps were monitored by the C1q binding assay and the purified material was analyzed by SDS--PAGE and immunodiffusion. The C1q binding material isolated from two breast cancer sera contained complexes of IgM, C4b binding protein (C4-bp), and C1q. The C4-bp fraction showed significant C1q binding activity which increased after the addition of IgM. This C4-bp was not different from C4-bp isolated from normal serum. The IgM fraction, however, differed from normal IgM by its binding to C4-bp and C1q and its stronger affinity to the cation exchange column. These unique properties were not due to rheumatoid factor activity. They might be caused by a different glycosylation pattern or by complex formation with an as yet unknown polysaccharide antigen.
本研究的目的是分离并鉴定通过125I-C1q结合试验在乳腺癌血清中检测到的免疫复合物。C1q结合试验通过免疫复合物与125I-C1q的结合以及随后用聚乙二醇沉淀来检测免疫复合物。我们通过Superose 6凝胶过滤和阳离子交换色谱从这些沉淀物中纯化C1q结合物质。通过C1q结合试验监测分离步骤，并用SDS-PAGE和免疫扩散分析纯化的物质。从两份乳腺癌血清中分离出的C1q结合物质含有IgM、C4b结合蛋白（C4-bp）和C1q的复合物。C4-bp部分显示出显著的C1q结合活性，添加IgM后该活性增强。这种C4-bp与从正常血清中分离出的C4-bp没有差异。然而，IgM部分与正常IgM的不同之处在于其与C4-bp和C1q的结合以及对阳离子交换柱更强的亲和力。这些独特性质并非由类风湿因子活性所致。它们可能是由不同的糖基化模式或与一种尚未知晓的多糖抗原形成复合物引起的。
