Seissler J, Amann J, Mauch L, Haubruck H, Wolfahrt S, Bieg S, Richter W, Holl R, Heinze E, Northemann W
Department of Internal Medicine, University of Ulm, Germany.
J Clin Invest. 1993 Sep;92(3):1394-9. doi: 10.1172/JCI116714.
We investigated the presence of autoantibodies to baculovirus-expressed human recombinant 65- and 67-kD isoforms of glutamate decarboxylase (GAD65 and GAD67) in insulin-dependent diabetes mellitus (IDDM). In the immunoprecipitation test using [35S]methionine-labeled GADs antibodies to GAD65 were detected in 13/15 (87%) islet cell antibody (ICA)-positive and in 1/35 (2.9%) ICA-negative first-degree relatives of patients with IDDM, in 6/11 (54.5%) ICA-positive nondiabetic schoolchildren, and in 35/50 (70%) patients with newly diagnosed IDDM. GAD67 antibodies were positive only in five (33%) of the ICA-positive relatives (P < 0.05) and in nine (18%) IDDM patients at onset (P < 0.00001). After onset of IDDM antibodies to GAD65 and GAD67 declined but were still positive in 25 and 9.4% of subjects with long-standing IDDM (> 10 yr). In all study groups antibodies to GAD67 were only detected in GAD65 antibody-positive sera. An immunotrapping enzyme activity assay for GAD65 antibodies was positive in 64/75 (85.3%) of sera that were GAD antibody positive in the immunoprecipitation test (r = 0.870, P < 0.0001). In two (2.7%) sera GAD65 antibodies that block GAD enzyme activity were found. Our data suggest that antibodies to GAD65 but not to GAD67 represent sensitive markers for preclinical and overt IDDM. The immunotrapping assay here described represents a valuable technique for specific and sensitive screening for GAD antibodies.
我们研究了胰岛素依赖型糖尿病（IDDM）患者体内针对杆状病毒表达的人重组65-kD和67-kD谷氨酸脱羧酶（GAD65和GAD67）亚型的自身抗体情况。在使用[35S]甲硫氨酸标记的GADs进行的免疫沉淀试验中，在13/15（87%）胰岛细胞抗体（ICA）阳性的IDDM患者一级亲属、1/35（2.9%）ICA阴性的IDDM患者一级亲属、6/11（54.5%）ICA阳性的非糖尿病学童以及35/50（70%）新诊断的IDDM患者中检测到了针对GAD65的抗体。GAD67抗体仅在5名（33%）ICA阳性亲属中呈阳性（P<0.05），在9名（18%）发病初期的IDDM患者中呈阳性（P<0.00001）。IDDM发病后，针对GAD65和GAD67的抗体水平下降，但在病程超过10年的长期IDDM患者中，仍有25%和9.4%呈阳性。在所有研究组中，仅在GAD65抗体阳性血清中检测到GAD67抗体。在免疫沉淀试验中GAD抗体阳性的75份血清中，64份（85.3%）的GAD65抗体免疫捕获酶活性测定呈阳性（r = 0.870，P<0.0001）。在两份（2.7%）血清中发现了可阻断GAD酶活性的GAD65抗体。我们的数据表明，针对GAD65而非GAD67的抗体是临床前期和显性IDDM的敏感标志物。本文所述的免疫捕获测定法是一种用于特异性和灵敏筛选GAD抗体的有价值技术。
