部分特发性1型糖尿病存在谷氨酸脱羧酶65反应性T细胞

目的探讨特发性1型糖尿病（1B型糖尿病）患者是否存在胰岛自身抗原反应性T细胞。方法选择经典1型糖尿病（1A型糖尿病）患者23例,1B型糖尿病29例,健康对照16例;放射配体法检测胰岛自身抗体;连续密度梯度离心法分离人外周血单个核细胞;酶联免疫斑点法（ELISPOT）检测谷氨酸脱羧酶（GAD65）反应性、分泌γ干扰素（IFN-γ）的T细胞（IFN-γ-T细胞）。结果（1）IFN-γ-T细胞数（中位数及95％CI表示）1A型糖尿病为：12．0个（10．3～20．9个）,1B型糖尿病：3．5个（3．0～5．7个）,对照：1．0个（0．3～1．8个）。1A型糖尿病的IFN-γ-T细胞数明显高于1B型糖尿病及对照（均P〈0．01）。1B型糖尿病较对照具有更高频率的IFN-γ-T细胞（P〈0．05）。（2）以〉95％CI（对照组）判为IFN-γ-T阳性,1A型糖尿病、1B型糖尿病及对照的阳性率分别为：78．3％（18／23）、48．3％（14／29）及0。（3）3组对植物血凝素非特异性刺激的IFN-γ-T细胞数差异无统计学意义（P〉0．05）。结论部分1B型糖尿病患者存在GAD65反应性IFN-γ-T细胞,即存在T细胞免疫异常,具有与1A型糖尿病相似的病因及发病机制;诊断1B型糖尿病前应排除IFN-γ-T阳性患者,GAD65 IFN-γ-T检测有望成为糖尿病分型诊断的新指标。

Detection of GAD65 reactive T cells in some Chinese subjects initially diagnosed as with idiopathic type 1 diabetes

OBJECTIVE: To demonstrate the existence of islet-associated antigen-specific T cells in some of type 1B patients. METHODS: Peripheral blood samples were obtained from 23 classical type 1 diabetes (Type 1A) patients, 29 type 1B patients, and 16 healthy control subjects. Islet-associated autoantibodies were determined by radioligand assay. Human peripheral blood mononuclear cells were isolated by Ficoll-Hypaque density gradients and enzyme linked immune spot (ELISPOT) assay was performed to measure the number of spots-forming plaque. One spot-forming represents a GAD65-reactive IFN-gamma-secreting T (IFN-gamma-T) cell. RESULTS: The IFN-gamma-spot numbers stimulated with GAD65 were 12 (10.3-20.9) (median and 95% CI) in Type 1A group, 3.5 (3.0-5.7) in Type 1B group, and 1.0 (0.3-1.8) in Control group respectively. The frequency of spots significantly increased in Type 1B group compared to Control group (P<0.05) and there were significantly more spot numbers in Type 1A group than in Type 1B or Control group (both P<0.01). A positive response was determined when the spot number>95% CI of Control subjects. 48.3% (14 of 29) in Type 1B group, 78.3% (18 of 23) in Type 1A and no subject (0) in Control group had positive response, while the numbers of IFN-gamma-spot reactive to phytohemagglutinin (PHA) did not differ among the three groups. CONCLUSION: GAD65-reactive IFN-gamma-T cells are found in similar to Type 1A patients, that abnormal T cell-mediated immunity involved in the underlying aetiology and pathogenesis is also present in some Chinese patients initially diagnosed as with Type 1B diabetes. More rigorous screening for these conditions is needed before classifying subjects as having Type 1B diabetes and ELISPOT assay detecting IFN-gamma-T cells reactivity against GAD65 may contribute to the diagnosis of "autoimmune diabetes mellitus".