Bender Christine, Schlosser Michael, Christen Urs, Ziegler Anette G, Achenbach Peter
Pharmazentrum Frankfurt/ZAFES, Goethe University Hospital Frankfurt, Theodor-Stern Kai 7, 60590, Frankfurt am Main, Germany,
Diabetologia. 2014 Sep;57(9):1911-8. doi: 10.1007/s00125-014-3294-9. Epub 2014 Jun 18.
AIMS/HYPOTHESIS: Subtyping GAD autoantibody (GADA) responses using affinity measurement allows the identification of GADA-positive children with a family history of type 1 diabetes who are at risk of developing diabetes. Here, we asked whether GADA affinity is a useful marker to stratify the risk of type 1 diabetes in GADA-positive schoolchildren from the general population.
GADA affinity was measured by competitive binding experiments with [(125)I]-labelled and unlabelled human 65 kDa isoform of GAD (GAD65) in sera from 97 GADA-positive children identified in the Karlsburg Type 1 Diabetes Risk Study of a general schoolchild population in north-eastern Germany. GADA epitope specificity was determined using radiobinding assays with [(35)S]-labelled GAD65/67 kDa isoform of GAD (GAD67) chimeric proteins.
GADA affinity was high, ≥ 10(10) l/mol, in 33 of 35 multiple islet autoantibody-positive children. In contrast, the affinity ranged widely among 62 single GADA-positive children (median 3.1 × 10(9) l/mol; range 5.6 × 10(6) to >4.0 × 10(11) l/mol; p < 0.0001). High-affinity GADA were associated with HLA-DRB1*03 (p = 0.02) and predominantly directed against the C-terminal and/or middle part of the GAD65 protein. At follow-up, the affinity remained relatively constant. Five of the single GADA-positive children developed additional islet autoantibodies and had high-affinity GADA. Twenty-six children progressed to type 1 diabetes; among them, 23 had GADA affinities of ≥ 10(10) l/mol before disease onset.
CONCLUSIONS/INTERPRETATION: Schoolchildren from the general population may develop heterogeneous GADA responses, and a high affinity can identify those GADA-positive children who are more likely to progress to type 1 diabetes.
目的/假设：利用亲和力测量对谷氨酸脱羧酶自身抗体（GADA）反应进行亚型分类，能够识别出有1型糖尿病家族史且有患糖尿病风险的GADA阳性儿童。在此，我们探讨GADA亲和力是否是对普通人群中GADA阳性学童1型糖尿病风险进行分层的有用标志物。
在德国东北部一项针对普通学童人群的卡尔斯堡1型糖尿病风险研究中，从97名GADA阳性儿童的血清中，通过与[（125）I]标记和未标记的人65 kDa谷氨酸脱羧酶（GAD65）异构体进行竞争性结合实验来测量GADA亲和力。使用[（35）S]标记的GAD65/67 kDa谷氨酸脱羧酶（GAD67）嵌合蛋白的放射结合测定法来确定GADA表位特异性。
在35名多种胰岛自身抗体阳性儿童中，有33名的GADA亲和力较高，≥10（10）l/mol。相比之下，62名单一GADA阳性儿童的亲和力范围广泛（中位数为3.1×10（9）l/mol；范围为5.6×10（6）至>4.0×10（11）l/mol；p<0.0001）。高亲和力GADA与HLA-DRB1*03相关（p = 0.02），且主要针对GAD65蛋白的C末端和/或中间部分。在随访中，亲和力保持相对稳定。5名单一GADA阳性儿童出现了其他胰岛自身抗体，且具有高亲和力GADA。26名儿童进展为1型糖尿病；其中，23名在疾病发作前GADA亲和力≥10（10）l/mol。
结论/解读：普通人群中的学童可能会产生异质性的GADA反应，高亲和力可以识别出那些更有可能进展为1型糖尿病的GADA阳性儿童。
