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

混合性结缔组织病（mixed connective tissue disease，MCTD）是一种典型的系统性自身免疫性疾病，对snRNP，尤其是70 kD多肽具有特异性的自身免疫反应。人类免疫应答，包括自身免疫，是通过将结合在HLA抗原结合沟上的表位肽呈递给T细胞而引发的。结合HLA特异性的肽共享混杂序列。为了建立一种策略，开发特异性和无害的武器来对抗这种疾病，我们首先分析了MCTD患者与HLA表型之间的关联，发现HLA-DR 2/DR 4与白人MCTD患者有共同的表位关联，HLA-DR 9与日本患者有关联。其次，我们在70 kD多肽中寻找HLA结合基序序列，在多肽的RNA结合区找到四个序列，并合成了20聚体多肽。第三，我们利用这些肽进行了70 kD多肽刺激的MCTD患者的T细胞系的增殖反应试验，我们在这里证明了这些肽可以调节患者的自身免疫反应，并显示这些肽作为候选表位治疗的可行性，这些肽应该是疾病特异性的，并且不良反应较小，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小鼠中以建立对70 kD多肽的自身免疫和MCTD的动物模型，并且我们成功地建立了产生人免疫球蛋白的小鼠，其也可以用作筛选针对snRNP的自身免疫的治疗性调节剂的那些肽的工具。

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.