Regulation of Autoimmunity through synthetic peptides deduced from HLA allele-specific binding motifs.

混合性结缔组织病（MCTD）是一种典型的全身性自身免疫性疾病，具有对snRNP，特别是对70kd多肽的特异性自身免疫反应的特点。人类的免疫反应，包括自身免疫，是由结合HLA抗原结合槽的表位肽呈递到T细胞而引发的。与HLA特异性结合的肽共享混杂的序列。为了建立一种开发特异性和无害武器来对抗疾病的策略，我们首先分析了MCTD患者与HLA表型之间的关系，发现HLA- dr2 /DR4与高加索MCTD患者有共同的表位关联，HLA- dr9与日本患者有共同的表位关联。其次，我们在70kD多肽内搜索HLA结合基序序列，在该多肽的RNA结合区找到4个序列，合成了20mer多肽。第三，利用这些多肽对70kD多肽刺激的高加索MCTD患者T细胞系进行增殖反应试验。我们在这里证明了这些肽可以调节患者的自身免疫反应，并展示了这些肽作为表位治疗候选的可行性，这些表位治疗应该是疾病特异性的，副作用较小，因为这些肽基本上是自身抗原。最后，我们将外周血单核细胞引入SCID小鼠，建立70kD多肽和MCTD自身免疫的动物模型，并成功建立了产生人免疫球蛋白的小鼠模型，该模型也可作为筛选snRNP自身免疫治疗调节剂的工具。

Mixed connective tissue disease, MCTD,is one of prototypic systemic autoimmune diseases, and has a characteristic of specific autoimmune responses to snRNP,especially to 70 kD polypeptide. Human immune responses, including autoimmunity, are ignited by the presentation of epitopic peptides bound on HLA antigen binding groove to T cells. The peptides, bound to an HLA specificity, share promiscuous sequences. To establish a strategy to develop specific and harmless weapons to fight against the disease, we first analyzed the association between patients with MCTD and HLA phenotypes, and found HLA-DR2/DR4 shared epitope association with Caucasian patients with MCTD,and HLA-DR9 association with Japanese patients. Secondly, we searched sequences of HLA binding motifs within the 70kD polypeptide, found four sequences within RNA binding region of the polypeptide, and synthesized the 20mer peptides. Thirdly, those peptides were utilized for the proliferative response assay of 70kD palypeptide stimulated T cell lines from a Caucasian patient with MCTD.We demonstrate here that those peptides could modulate the autoimmune response of the patients, and show feasibility of those peptides as candidates for epitope therapy which should be disease-specific and of less adverse effects because those peptides are basically autoantigens. Lastly, we introduced peripheral blood mononucleated cells into SCID mice to establish animal models for autoimmunity to the 70kD polypeptide and for MCTD,and we successfully established the mice producing human immunoglobulins, which could also serve as tools to screen those peptides for therapeutic modulators of autoimmunity to snRNP.