Matsuda M, Shikata K, Wada J, Sugimoto H, Shikata Y, Kawasaki T, Makino H
Department of Medicine III, Okayama University Medical School, Okayama, Japan.
Nephron. 1998 Dec;80(4):408-13. doi: 10.1159/000045212.
Mannan binding protein (MBP) is a C-type lectin and has a high affinity to mannose and N-acetyl glucosamine. It is also known to activate C4 and C2 without C1 component, which is called 'lectin pathway'. We now report the presence of MBP and MBP-mediated complement activation in renal glomeruli of IgA nephropathy patients using an immunohistochemical method. In 7 of 42 cases with IgA nephropathy, MBP was detected in the glomerular mesangial area and colocalized with IgA1. In 19 cases with other types of IC-mediated glomerulonephritis including lupus nephritis and membranous nephropathy or without nephritis, MBP was not detected in the glomerulus. The C2- and/or C4-positive rate was 87.5% in the MBP-positive group and 20% in the MBP-negative group of IgA nephropathy. In addition, MBP-positive cases showed marked mesangial cell proliferation, lower creatinine clearance (53.4 +/- 10.0 vs. 77. 8 +/- 4.7 ml/min) and higher urinary protein excretion (2.5 +/- 0.9 vs. 0.9 +/- 0.2 g/day) compared with MBP-negative cases. These findings suggested that MBP was involved in glomerular complement activation through the lectin pathway and thus induced glomerular injury of IgA nephropathy. Since oligosaccharide chain alterations such as reduced sialic acid and galactose of IgA1 molecule have been reported in IgA nephropathy patients, MBP might bind to the IgA1 molecule via interaction between MBP and sugar chain.
甘露聚糖结合蛋白（MBP）是一种C型凝集素，对甘露糖和N-乙酰葡糖胺具有高亲和力。已知它可在无C1成分的情况下激活C4和C2，这一过程被称为“凝集素途径”。我们现在报告，使用免疫组织化学方法在IgA肾病患者的肾小球中检测到了MBP以及MBP介导的补体激活。在42例IgA肾病患者中，有7例在肾小球系膜区检测到MBP，且与IgA1共定位。在19例其他类型的免疫复合物介导的肾小球肾炎患者中，包括狼疮性肾炎、膜性肾病患者或无肾炎患者，肾小球中未检测到MBP。在IgA肾病的MBP阳性组中，C2和/或C4阳性率为87.5%，MBP阴性组为20%。此外，与MBP阴性病例相比，MBP阳性病例显示出明显的系膜细胞增殖、较低的肌酐清除率（53.4±10.0对77.8±4.7 ml/分钟）和较高的尿蛋白排泄量（2.5±0.9对0.9±0.2 g/天）。这些发现表明，MBP通过凝集素途径参与肾小球补体激活，从而导致IgA肾病的肾小球损伤。由于在IgA肾病患者中已报道了IgA1分子的寡糖链改变，如唾液酸和半乳糖减少，MBP可能通过MBP与糖链之间的相互作用与IgA1分子结合。
