Chaillous L, Delamaire M, Martignat L, Maugendre D, Marre M, Mathieu E, Limal J M, Charbonnel B, Allannic H, Saï P
Laboratoire Universitaire d'Immuno-Endocrinologie Associé INRA/ENVN, Nantes, France.
Diabetes Care. 1994 Oct;17(10):1115-23. doi: 10.2337/diacare.17.10.1115.
A combined analysis of whether islet cell autoantibodies (ICAs) are cross-reactive with mouse pancreas, with glutamate decarboxylase (GAD) antibodies, and with 64K antibodies was performed in a large sample of recently diagnosed type I diabetic patients. The disappearance rates of these different autoantibodies were compared in some patients after onset of the disease. The aims were to determine patterns in GAD/64K antibodies with regard to cross-species reaction of ICA and to assess whether GAD could contribute to ICA positivity in mouse and human pancreases and whether the simultaneous search for all the antibody specificities enhances the detection of autoimmune stigma.
ICA detected by immunofluorescence in human and mouse pancreases, antibodies immunoprecipitating the 64K rat islet antigen, and antibodies immunotrapping brain GAD activity were quantified at diagnosis of diabetes in 95 patients and in sequential samples during 1 year after diagnosis in 13 patients. The contribution of GAD to ICA positivity in mouse and human pancreases was evaluated by the analysis of correlations between tests and by the ability of brain homogenate to block ICA reactivity in pancreases from both species.
ICAs were detected in human pancreases in sera from 63 (66%) patients, among which 61% bound also to a mouse pancreas. GAD and 64K antibodies were strongly correlated (P < 0.0001) and were detected in 69 and 73% of the patients, respectively. All but two patients with ICA in human pancreas also displayed either ICA in mouse pancreas or GAD/64K antibodies. Among 32 patients without ICA in human pancreas, 54% displayed either GAD/64K antibodies or ICA in mouse pancreas. Only 16% of the patients displayed neither ICA nor GAD/64K antibodies. A correlation (P < 0.005) was found between ICA in human and mouse pancreases. GAD or 64K antibodies were strongly correlated with ICA in human pancreas (P < 0.0001), but not with ICA in mouse pancreas. After preincubation of six sera with GAD-containing brain homogenate, ICA titers were unaffected in mouse pancreas but reduced in human pancreas. ICA titers in mouse pancreas were decreased after 3 months (P < 0.01) in diabetic patients, contrasting with the stability of ICA in human pancreas and GAD antibodies by 1 year after diagnosis.
According to cross-species reaction, we confirm the heterogeneity of ICA in a large series of type I diabetic patients, ICAs that cross-reacted with mouse pancreas being more frequent than ICAs without cross-species reactivity. GAD and 64K antibodies were also present in a majority of patients. The simultaneous search for all the antibody specificities enhances the detection of autoimmune stigma so that only a few patients did not display any autoantibody at diagnosis. GAD is not the target of ICAs in mouse pancreas, whereas GAD accounts for ICA positivity in human pancreas. The conclusion that ICAs in mouse pancreas are not GAD-reactive is reinforced by the fact that they are more transient after onset of diabetes than are GAD antibodies or the complex mixture of ICAs in human pancreas.
对大量新诊断的I型糖尿病患者进行联合分析，以研究胰岛细胞自身抗体（ICA）是否与小鼠胰腺、谷氨酸脱羧酶（GAD）抗体及64K抗体发生交叉反应。比较了部分患者发病后这些不同自身抗体的消失率。目的是确定GAD/64K抗体在ICA跨物种反应方面的模式，评估GAD是否会导致小鼠和人类胰腺中ICA呈阳性，以及同时检测所有抗体特异性是否能增强对自身免疫特征的检测。
对95例糖尿病患者诊断时以及13例患者诊断后1年内的连续样本，通过免疫荧光法检测人及小鼠胰腺中的ICA、免疫沉淀64K大鼠胰岛抗原的抗体以及免疫捕获脑GAD活性的抗体。通过分析检测结果之间的相关性以及脑匀浆阻断两种物种胰腺中ICA反应性的能力，评估GAD对小鼠和人类胰腺中ICA阳性的贡献。
63例（66%）患者血清中的ICA在人胰腺中被检测到，其中61%也与小鼠胰腺结合。GAD和64K抗体高度相关（P<0.0001），分别在69%和73%的患者中被检测到。除两名患者外，人胰腺中有ICA的所有患者在小鼠胰腺中也显示出ICA或GAD/64K抗体。在32例人胰腺中无ICA的患者中，54%在小鼠胰腺中显示出GAD/64K抗体或ICA。仅16%的患者既无ICA也无GAD/64K抗体。人胰腺和小鼠胰腺中的ICA之间存在相关性（P<0.005）。GAD或64K抗体与人胰腺中的ICA高度相关（P<0.0001），但与小鼠胰腺中的ICA无关。用含GAD的脑匀浆预孵育6份血清后，小鼠胰腺中的ICA滴度未受影响，但人胰腺中的ICA滴度降低。糖尿病患者发病3个月后小鼠胰腺中的ICA滴度下降（P<0.01），这与诊断后1年人胰腺中ICA和GAD抗体的稳定性形成对比。
根据跨物种反应，我们证实在大量I型糖尿病患者中ICA具有异质性，与小鼠胰腺发生交叉反应的ICA比无跨物种反应性的ICA更常见。大多数患者也存在GAD和64K抗体。同时检测所有抗体特异性可增强对自身免疫特征的检测，因此在诊断时只有少数患者未显示任何自身抗体。GAD不是小鼠胰腺中ICA的靶点，而GAD是人胰腺中ICA阳性的原因。糖尿病发病后小鼠胰腺中的ICA比GAD抗体或人胰腺中ICA的复杂混合物更短暂，这一事实进一步证明小鼠胰腺中的ICA与GAD无反应性。
