中文摘要：

目的研究T细胞与胰岛素瘤相关蛋白2（IA-2）构象限制性表位之间的相互作用，比较IA-2表位空间构象和氨基酸一级序列在B-T细胞相互作用中所起作用的差别。方法设计合成四种IA-2843-855表位多肽，分别为13折叠结构的野生亲本多肽、改变氨基酸排列顺序得到的α螺旋结构（构象变异性）、改变氨基酸排列顺序得到的无规则卷曲结构（无序结构型）以及通过引入34＂疏水氨基酸得到的更具有B折叠结构的多肽（序列变异型），选取IA-2抗体阳性的I型糖尿病（T1DM）、2型糖尿病（T2DM）患者各12例及健康志愿者12名为研究对象，采取外周血单个核细胞并给予四种不同结构IA-2843-855刺激，分别计算各组的刺激指数（SI）及各组细胞被刺激后分泌细胞因子白细胞介素（IL）4及IL-2的水平，组间比较采用t检验。结果与T2DM组比较，IA-2843-855多肽、d螺旋结构、无规则卷曲结构、更具B折叠结构的刺激指数在T1DM组升高，差异均有统计学意义（分别为1．33±0．05比1．13±0．06，1．27±0．06比1．19±0．05，1．31±0．07比1．21±0．05，1．20±0．07比1．11±0．05，t=-11．60～-2．71，均P〈0．05），TIDM组与健康对照组相比较亦升高，差异亦有统计学意义（t=-12．60- -2．12，均P〈0．05）；四种多肽刺激T1DM组T淋巴细胞分泌IL-4水平较T2DM组及健康对照组均降低，差异均有统计学意义（t=2．43～11．75，均P〈0．05）；同时这四种多肽刺激T1DM组T淋巴细胞分泌IL-2水平与T2DM组及健康对照组比较均升高，差异均有统计学意义（t=7．20- -2．14，均P〈0．05）；序列变异型多肽对T1DM组淋巴细胞的增殖影响与其他三组比较均有所下降（t=2．41-3．72，均P〈0．05），刺激T细胞分泌细胞因子IL-2与其他三组比较均有所下降（t=2．09-4．91，均P〈0．05），刺激T细胞分泌细胞因子IL-4的水平与其他三种多肽相?

英文摘要：

Objective To explore the interaction of T cell and insulinoma-associated protein 2 （IA-2） conformation and peptide primary sequence on B and T lymphocyte. Methods We designed and synthesized four types of IA-2 epitope peptides, parental [5-fold structure IA-2～3_s55 peptide, a-helical IA-2s43_s55 peptide （conformation variability）, random coil IA-284～-s55 peptide （sequence variance） and further [～-fold structure IA-2s43-8～5 peptide which incorporated three hydrophobic amino acid. Patients who werediagnosed as type 1 diabetes mellitus （T1DM, n=12） within 1 year and with high titer IA-2 autoantibodies, T2DM （n=12） and healthy control（n=12） were recruited from the second hospital of Jilin university. Their peripheral blood mononuclear cell （PBMC） ceils were stimulated with four types of IA-2843-855 antigens（ 10 ttg/ ml） and nonspecific mitogen PHA （5 t～g/ml） was added as positive control. Cellular proliferation was expressed as the stimulation index（SI）. The suspensions collected from culture medium after centrifuged were used to test the levels of cytokines interleukin （IL）-2 and IL-4. T-test was used to compare the means between groups. Results The SI of T1DM stimulated by parental 13-fold structure IA-2_843-855 peptide, the a-helical IA-2_843-855 peptide, the random coil IA-2_843-855 peptide and the further β-fold structure IA-2_843-855 peptide were significantly higher than those in T2DM（1.33 ± 0.05 vs 1.13 ～ 0.06, 1.27±0.06 vs 1.19 ～ 0.05, 1.31±0.07 vs 1.21±0.05, 1.20±0.07 vs 1.11 ～0.05, respectively, t=-ll.6--2.71,P〈0.05）, and also significantly higher than that in the healthy group （t=-12.6--2.12,P〈O.05）. The IL-4 level of T1DM stimulated by the four types of IA-28～3_843-855peptide were significantly lower than that in T2DM and the healthy group（t=2.43-11.75, all P〈0.05）. The IL-2 level of T1DM stimulated by the four types of IA-2_843～855 peptide were significantly higher than that in T2DM and the healthy group（t=-7.20--2