Tuveson D A, Ahearn J M, Matsumoto A K, Fearon D T
Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
J Exp Med. 1991 May 1;173(5):1083-9. doi: 10.1084/jem.173.5.1083.
The complement system augments the humoral immune response to low concentrations of antigen. This effect may be partly mediated by complement receptors on the surface of B lymphocytes that bind immunogenic complexes bearing fragments of C3 and C4. We have shown by immunoprecipitation analysis that the two complement receptors expressed by B lymphocytes, complement receptor 1 (CR1) and CR2, form a detergent-sensitive complex on the surface of tonsillar B lymphocytes and on K562 erythroleukemia cells that were co-transfected with cDNAs encoding CR1 and CR2. The CR1/CR2 complex is distinct from the CR2/CD19 complex and may assist B cell activation by efficiently capturing C3b-containing immunogens and maintaining such immunogens on the B cell after CR1 and factor I-mediated cleavage to iC3b and C3dg. The complement activating immunogen may then trigger signal transduction by the CR1/CR2 complex, the CR2/CD19 complex, or membrane immunoglobulin.
补体系统增强了机体对低浓度抗原的体液免疫反应。这种效应可能部分由B淋巴细胞表面的补体受体介导，这些受体可结合带有C3和C4片段的免疫原性复合物。我们通过免疫沉淀分析表明，B淋巴细胞表达的两种补体受体，即补体受体1（CR1）和CR2，在扁桃体B淋巴细胞表面以及与编码CR1和CR2的cDNA共转染的K562红白血病细胞表面形成了一种对去污剂敏感的复合物。CR1/CR2复合物不同于CR2/CD19复合物，它可能通过有效捕获含C3b的免疫原并在CR1和I因子介导的裂解形成iC3b和C3dg后将此类免疫原维持在B细胞上，从而协助B细胞活化。补体激活免疫原随后可通过CR1/CR2复合物、CR2/CD19复合物或膜免疫球蛋白触发信号转导。
