Jaskowski T D, Martins T B, Litwin C M, Hill H R
Associated Regional and University Pathologists (ARUP) Institute for Clinical and Experimental Pathology, Salt Lake City, Utah 84108, USA.
J Clin Lab Anal. 2004;18(4):247-50. doi: 10.1002/jcla.20031.
The presence of immunoglobulin (Ig)M antibody against myelin associated glycoprotein (MAG) has been associated with autoimmune demyelinating, sensorimotor neuropathies. Approximately 50% of patients with IgM paraproteinemia and associated peripheral neuropathy possess antibodies against MAG. These autoantibodies are thought to interfere with the process of myelination, myelin maintenance, or axon-Schwann cell interaction. The detection of these autoantibodies is useful to the clinician and is suggestive of active demyelination in a peripheral neuropathy. Our objective in this study was to compare the results obtained using three different methods (dual enzyme immunoassay [EIA], immunofluorescent antibody [IFA] and Western blot [WB]) for detecting IgM antibody against MAG in patients suspected of having autoimmune demyelinating neuropathies. Since the dual EIA utilized two different antigens, results from this assay were separated into two groups: MAG and sulfate-3-glucuronyl paragloboside (SGPG). When compared to WB (gold standard), percent agreement, sensitivity, and specificity for EIA and IFA are as follows: MAG EIA (68.3, 100.0, and 60.6); SGPG EIA (95.1, 100.0, and 93.9); and myelin IFA (97.6, 100.0, and 97.0). The authors conclude that the SGPG EIA and myelin IFA compared well with the standard WB method when detecting IgM antibody against MAG (100 kD). Many sera demonstrated reactivity on the MAG EIA that were negative by WB (100 kD glycoprotein). The authors recommend screening for MAG IgM in suspected patient sera by SGPG EIA or myelin IFA and utilizing these same methods to titer sera confirmed positive by WB.
抗髓鞘相关糖蛋白（MAG）免疫球蛋白（Ig）M抗体的存在与自身免疫性脱髓鞘感觉运动性神经病有关。约50%的IgM副蛋白血症及相关周围神经病患者存在抗MAG抗体。这些自身抗体被认为会干扰髓鞘形成、髓鞘维持或轴突-施万细胞相互作用的过程。检测这些自身抗体对临床医生很有用，提示周围神经病存在活动性脱髓鞘。本研究的目的是比较三种不同方法（双酶免疫测定法[EIA]、免疫荧光抗体法[IFA]和蛋白质印迹法[WB]）检测疑似自身免疫性脱髓鞘神经病患者抗MAG IgM抗体的结果。由于双EIA使用了两种不同抗原，该检测结果分为两组：MAG和硫酸-3-葡糖醛酸副球蛋白（SGPG）。与WB（金标准）相比，EIA和IFA的一致性百分比、敏感性和特异性如下：MAG EIA（68.3、100.0和60.6）；SGPG EIA（95.1、100.0和93.9）；髓鞘IFA（97.6、100.0和97.0）。作者得出结论，在检测抗MAG（100 kD）IgM抗体时，SGPG EIA和髓鞘IFA与标准WB方法相比效果良好。许多血清在MAG EIA上呈反应性，但WB（100 kD糖蛋白）检测为阴性。作者建议通过SGPG EIA或髓鞘IFA对疑似患者血清进行MAG IgM筛查，并使用相同方法对WB确诊为阳性的血清进行滴度测定。
