Doi T, Kanatsu K, Mayumi M, Hamashima Y, Yoshida H
Department of Pathology, Faculty of Medicine, Kyoto University, Japan.
Nephron. 1991;57(2):131-6. doi: 10.1159/000186239.
The levels of circulating immune complexes (CIC) were determined using an anti-C3d binding assay in patients with various types of glomerulonephritis (GN). It was found that IgG class CIC were positive in 20% (7/35) of patients with idiopathic membranous nephropathy (MN) and in 80% (8/10) of patients with lupus glomerulonephritis (LN). Of these patients, IgG4 subclass CIC were observed more frequently in 29% of MN and 60% (3/5) of minimum change nephrotic syndrome, and, with less amounts, in 10% (1/10) of membranoproliferative GN (MPGN) and 20% (2/10) of IgA nephropathy. On the other hand, the patients with LN showed a lower positivity (30%) of IgG4-CIC as compared with that of IgG-CIC. In the comparison of mean levels, only MN patients showed significantly higher value than normal individuals (p less than 0.05). In patients with MN, the CIC of the other IgG subclasses (IgG1, IgG2, IgG3) were not significantly elevated and their positivities were low (9-11%). The study on the salt-dependent dissociability of CIC, which is considered to reflect the avidity of antibodies in CIC, showed that the IgG-CIC of 11 of 15 patients with MN were dissociable to various extents even at the physiological concentration. These findings suggested that IgG4 subclass specificity and low avidity may be pathogenic characteristics of IgG-CIC in certain populations of patients with MN.
采用抗C3d结合试验测定了各类肾小球肾炎（GN）患者循环免疫复合物（CIC）的水平。结果发现，特发性膜性肾病（MN）患者中20%（7/35）的IgG类CIC呈阳性，狼疮性肾小球肾炎（LN）患者中80%（8/10）的IgG类CIC呈阳性。在这些患者中，IgG4亚类CIC在29%的MN患者和60%（3/5）的微小病变肾病综合征患者中更常见，而在膜增生性GN（MPGN）的10%（1/10）患者和IgA肾病的20%（2/10）患者中含量较少。另一方面，与IgG - CIC相比，LN患者的IgG4 - CIC阳性率较低（30%）。在平均水平比较中，只有MN患者的值显著高于正常个体（p小于0.05）。在MN患者中，其他IgG亚类（IgG1、IgG2、IgG3）的CIC没有显著升高，其阳性率较低（9 - 11%）。对CIC盐依赖性解离性的研究（该特性被认为反映了CIC中抗体的亲和力）表明，15例MN患者中有11例的IgG - CIC即使在生理浓度下也能在不同程度上解离。这些发现表明，IgG4亚类特异性和低亲和力可能是某些MN患者群体中IgG - CIC的致病特征。
