Congia M, Patel S, Cope A P, De Virgiliis S, Sønderstrup G
Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA.
Proc Natl Acad Sci U S A. 1998 Mar 31;95(7):3833-8. doi: 10.1073/pnas.95.7.3833.
Approximately one-half of Caucasians with newly diagnosed insulin-dependent diabetes mellitus (IDDM) have autoantibodies to insulin, and the majority of those express the HLA-DR4 genotype [Ziegler, R., Alper, C. A., Awdeh, Z. L., Castano, L., Brink, S. J., Soeldner, J. S., Jackson, R. A. & Eisenbarth, G. S. (1991) Diabetes 40, 709-714]. However, it has been difficult to demonstrate T cell proliferative responses to human insulin in IDDM patients [Durinovic-Bello, I., Hummel, M. & Ziegler, A. G. (1996) Diabetes 45, 795-800]. We have immunized transgenic mice expressing the susceptible HLA-DR (alpha10101,beta10401) (hereafter called DRB10401) and human CD4 molecules on a murine major histocompatibility complex class II null background, with human preproinsulin (PPI), proinsulin (PI), and insulin and derived large panels of T cell hybridomas to determine the immunogenic epitopes of these proteins. These results show that the prohormones PI or PPI carry the major immunogenic T cell epitope in the DRB10401 transgenic mice. The PPI/PI immunodominant epitope LALEGSLQK was localized at the C-peptide/A-chain junction. This T cell epitope PPI/PI LALEGSLQK is unusual because, normally, it is proteolytically destroyed during the maturation of the insulin molecule. Additionally, this T cell epitope is both processed and presented by human DRB1*0401-positive Epstein-Barr virus transformed B cells, and it can also stimulate T cells from the peripheral blood of HLA-DR4-positive patients with type 1 diabetes. These findings may partly explain why susceptibility to type 1 diabetes is associated with HLA-DR4-positive individuals and why T cell responses to the mature insulin protein are rarely detected in IDDM patients.
新诊断的胰岛素依赖型糖尿病（IDDM）患者中，约一半的高加索人具有胰岛素自身抗体，且其中大多数表达HLA - DR4基因型[齐格勒，R.，阿尔珀，C. A.，奥德，Z. L.，卡斯塔诺，L.，布林克，S. J.，索尔德纳，J. S.，杰克逊，R. A.和艾森巴思，G. S.（1991年）《糖尿病》40，709 - 714]。然而，在IDDM患者中很难证明对人胰岛素的T细胞增殖反应[杜里诺维奇 - 贝洛，I.，胡梅尔，M.和齐格勒，A. G.（1996年）《糖尿病》45，795 - 800]。我们用人类胰岛素原（PPI）、胰岛素原（PI）和胰岛素免疫了在小鼠主要组织相容性复合体II类基因缺失背景下表达易感HLA - DR（α10101，β10401）（以下称为DRB10401）和人类CD4分子的转基因小鼠，并获得了大量T细胞杂交瘤，以确定这些蛋白质的免疫原性表位。这些结果表明，激素原PI或PPI在DRB10401转基因小鼠中携带主要的免疫原性T细胞表位。PPI/PI免疫显性表位LALEGSLQK定位于C肽/A链连接处。这个T细胞表位PPI/PI LALEGSLQK很不寻常，因为通常它在胰岛素分子成熟过程中会被蛋白水解破坏。此外，这个T细胞表位可由人类DRB1*0401阳性的爱泼斯坦 - 巴尔病毒转化的B细胞加工和呈递，并且它还能刺激1型糖尿病HLA - DR4阳性患者外周血中的T细胞。这些发现可能部分解释了为什么1型糖尿病易感性与HLA - DR4阳性个体相关，以及为什么在IDDM患者中很少检测到对成熟胰岛素蛋白的T细胞反应。
