Department of Endocrinology, Jiangsu Province Hospital of TCM, Nanjing, Jiangsu, China.
PLoS One. 2012;7(2):e32515. doi: 10.1371/journal.pone.0032515. Epub 2012 Feb 24.
Overt autoantibodies to the smaller isoform of glutamate decarboxylase (GAD65Ab) are a characteristic in patients with Type 1 diabetes (T1D). Anti-idiotypic antibodies (anti-Id) directed to GAD65Ab effectively prevent the binding of GAD65 to GAD65Ab in healthy individuals. Levels of GAD65Ab-specific anti-Id are significantly lower in patients with T1D, leading to overt GAD65Ab in these patients. To determine the possible protective role of GAD65Ab-specific anti-Id in T1D pathogenesis, we developed the monoclonal anti-Id MAb 8E6G4 specifically targeting human monoclonal GAD65Ab b96.11. MAb 8E6G4 was demonstrated as a specific anti-Id directed to the antigen binding site of b96.11. MAb 8E6G4 recognized human antibodies in sera from healthy individuals, T2D patients, and T1D patients as established by ELISA. We confirmed these MAb 8E6G4-bound human antibodies to contain GAD65Ab by testing the eluted antibodies for binding to GAD65 in radioligand binding assays. These findings confirm that GAD65Ab are present in sera of individuals, who test GAD65Ab-negative in conventional detection assays. To test our hypothesis that GAD65Ab-specific anti-Id have an immune modulatory role in T1D, we injected young Non Obese Diabetic (NOD) mice with MAb 8E6G4. The animals were carefully monitored for development of T1D for 40 weeks. Infiltration of pancreatic islets by mononuclear cells (insulitis) was determined to establish the extent of an autoimmune attack on the pancreatic islets. Administration of MAb 8E6G4 significantly reduced the cumulative incidence rate of T1D and delayed the time of onset. Insulitis was significantly less severe in animals that received MAb 8E6G4 as compared to control animals. These results support our hypothesis that anti-Id specific to GAD65Ab have a protective role in T1D.
谷氨酸脱羧酶（GAD65）小同工型的自身抗体是 1 型糖尿病（T1D）患者的特征。针对 GAD65Ab 的抗独特型抗体（anti-Id）可有效阻止 GAD65 与健康个体中的 GAD65Ab 结合。T1D 患者的 GAD65Ab 特异性抗-Id 水平显著降低，导致这些患者出现明显的 GAD65Ab。为了确定 GAD65Ab 特异性抗-Id 在 T1D 发病机制中的可能保护作用，我们开发了针对人源单克隆 GAD65Ab b96.11 的单克隆抗-Id MAb 8E6G4。研究表明，该 MAb 8E6G4 是一种针对 b96.11 的抗原结合位点的特异性抗-Id。通过 ELISA 证实，该 MAb 8E6G4 可识别健康个体、2 型糖尿病患者和 T1D 患者血清中的人源性抗体。我们通过检测放射性配体结合试验中洗脱抗体与 GAD65 的结合情况，证实这些 MAb 8E6G4 结合的人源性抗体含有 GAD65Ab。这些发现证实 GAD65Ab 存在于常规检测呈 GAD65Ab 阴性的个体血清中。为了验证我们的假设，即 GAD65Ab 特异性抗-Id 在 T1D 中具有免疫调节作用，我们向年轻的非肥胖糖尿病（NOD）小鼠注射 MAb 8E6G4。仔细监测这些动物 40 周，以确定其是否发生 T1D。通过单核细胞浸润胰岛（胰岛炎）确定胰岛自身免疫攻击的程度。与对照动物相比，给予 MAb 8E6G4 可显著降低 T1D 的累积发病率并延迟发病时间。给予 MAb 8E6G4 的动物的胰岛炎明显较轻。这些结果支持我们的假设，即 GAD65Ab 特异性抗-Id 在 T1D 中具有保护作用。
