Bond A, Jones M G, Hay F C
Department of Cellular and Molecular Sciences, St. George's Hospital Medical School, London, UK.
J Immunol Methods. 1993 Nov 5;166(1):27-33. doi: 10.1016/0022-1759(93)90325-2.
IgG from patients with rheumatoid arthritis (RA) is abnormally glycosylated in the Fc region, with sialic acid and galactose levels lower than normal. Protein G and DEAE purify populations which are differentially glycosylated. Significantly increased exposure of sialic acid was detected in normal IgG compared with that of RA IgG when ion exchange was used to prepare samples. However, when the same samples were prepared using protein G, no difference in the detection of sialic acid was seen between the two groups. When examining the heavy chain of IgG, more sialic acid, galactose and N-acetylglucosamine were detected in DEAE purified IgG compared with that prepared by protein G Detection of sialic acid and N-acetylglucosamine was also increased on light chains from IgG prepared by ion exchange chromatography. Since this occurs notably on rheumatoid light chains it would appear that this arrangement would contribute to the overall glycosylation changes in IgG. In the case of molecules lacking galactose the discrimination between the RA and normal IgG is significantly improved when ion exchange chromatography is used. Since differentiation between disease and normal groups relies on the purification technique used, we recommend that more than one method is employed before undertaking an analysis of glycosylation changes.
类风湿关节炎（RA）患者的IgG在Fc区域存在异常糖基化，唾液酸和半乳糖水平低于正常水平。蛋白G和二乙氨基乙基（DEAE）可纯化不同糖基化的群体。当使用离子交换法制备样品时，与RA IgG相比，正常IgG中唾液酸的暴露显著增加。然而，当使用蛋白G制备相同样品时，两组之间唾液酸的检测没有差异。在检测IgG重链时，与蛋白G制备的IgG相比，DEAE纯化的IgG中检测到更多的唾液酸、半乳糖和N-乙酰葡糖胺。通过离子交换色谱法制备的IgG轻链上唾液酸和N-乙酰葡糖胺的检测也有所增加。由于这种情况在类风湿轻链上尤为明显，这种排列似乎会导致IgG整体糖基化变化。对于缺乏半乳糖的分子，当使用离子交换色谱法时，RA IgG与正常IgG之间的区分显著改善。由于疾病组和正常组之间的区分依赖于所使用的纯化技术，我们建议在进行糖基化变化分析之前采用多种方法。
