Tomana M, Matousovic K, Julian B A, Radl J, Konecny K, Mestecky J
Department of Medicine, University of Alabama at Birmingham, USA.
Kidney Int. 1997 Aug;52(2):509-16. doi: 10.1038/ki.1997.361.
IgA1 proteins from sera of patients with IgA nephropathy (IgAN) are galactosylated to a lesser degree than those from healthy controls. The increased reactivity of intact or de-sialylated serum IgA1 with N-acetylgalactosamine (GalNAc)-specific lectins, Helix aspersa (HAA) and Caragana arborescens (CAA) and de-sialylated IgA1 with Helix pomatia (HPA) and Bauhinia purpurea (BPA) indicated that the Gal deficiency is in glycans located in the hinge region of IgA1 molecules. De-sialylated IgA from sera of 81 IgAN patients bound biotin-labeled lectin HAA more effectively than did de-sialylated IgA from 56 healthy controls (P < 0.0001). Similar results were observed for 67 IgAN patients and 52 controls with second lectin, CAA (P < 0.001). The binding patterns for 9 patients with mesangial proliferative glomerulonephritis of non-IgA origin were similar to those for controls. Incompletely galactosylated IgA1 capable of binding GalNAc-specific lectins was detected in complexes with IgG as demonstrated by ELISA, size-exclusion chromatography and sucrose gradient ultracentrifugation. The formation of IgA1-IgG complexes may affect the serum level of IgA1 by reducing the rate of its elimination and catabolic degradation by the liver.
与健康对照者相比，IgA肾病（IgAN）患者血清中的IgA1蛋白半乳糖基化程度较低。完整的或去唾液酸化的血清IgA1与N-乙酰半乳糖胺（GalNAc）特异性凝集素（即欧洲大蜗牛凝集素（HAA）和锦鸡儿凝集素（CAA））以及去唾液酸化的IgA1与苹果蜗牛凝集素（HPA）和紫羊蹄甲凝集素（BPA）的反应性增加，表明半乳糖缺乏存在于IgA1分子铰链区的聚糖中。81例IgAN患者血清中的去唾液酸化IgA比56例健康对照者血清中的去唾液酸化IgA更有效地结合生物素标记的凝集素HAA（P<0.0001）。对于67例IgAN患者和52例对照者使用第二种凝集素CAA时，也观察到了类似结果（P<0.001）。9例非IgA起源的系膜增生性肾小球肾炎患者的结合模式与对照者相似。通过ELISA、尺寸排阻色谱法和蔗糖梯度超速离心法证实，在与IgG的复合物中检测到了能够结合GalNAc特异性凝集素的不完全半乳糖基化IgA1。IgA1-IgG复合物的形成可能通过降低肝脏对其清除和分解代谢降解的速率来影响IgA1的血清水平。
