T-CELL SPECIFICITY IN IMMUNITY AND AUTOIMMUNITY TO DNA

各种细胞抗原的抗体，主要是核抗原， 已经在患有系统性狼疮的小鼠和人类的血清中检测到 红斑有令人信服的证据表明这些自身抗体， 特别是DNA自身抗体，至少部分负责 狼疮的病理表现。免疫学基础 在小鼠和人类中产生抗DNA自身抗体是困难的 来阐明。先前尝试用相同的方法刺激抗体， 在狼疮中作为抗DNA抗体与DNA结合特异性， 不成功。这一事实加上普遍存在的 狼疮小鼠模型中淋巴细胞发育的异常导致 对于狼疮自身抗体不依赖于抗原而产生的提议， 多克隆B细胞活化。然而，最近的结果，从我们的分子 自身免疫性抗DNA抗体的结构和个体发生分析 已经表明，对DNA的自身免疫是启动和持续的， 对DNA或DNA复合物的克隆选择的特异性免疫反应。的 自身免疫性抗DNA抗体的二次免疫特性 提示抗原特异性辅助性T细胞参与了 这种自身抗体的产生，实验数据支持这一点 假说.然而，关于其特异性和功能知之甚少。 这样的T细胞。我们最近建立了一种实验性免疫 在小鼠中诱导DNA抗体的模型， 易患自身免疫性疾病本实验中使用的免疫原 系统是与DNA结合肽复合的DNA。诱导的抗- DNA抗体具有与DNA抗体相同的结构和特异性特征， 自身免疫性抗DNA抗体在狼疮中的作用。此外，小鼠生产 这种抗体发展出早期狼疮肾炎的症状。 本申请中提出的研究将开发新的 产生T细胞克隆和杂交体的实验免疫系统 特异于DNA结合肽。T细胞克隆和杂交将是 由正常、非自身免疫易感和自身免疫易感小鼠产生 用DNA-肽复合物免疫。这些克隆人和混血儿 用于确定辅助T细胞的特异性和功能， 当用以下物质刺激时，可以诱导体外抗DNA抗体产生 特异性DNA肽。特别是这些实验将确定 这些T细胞的MHC限制性T细胞表位是否由 单独的肽或DNA和肽的组合。实验 也将确定特定的氨基酸序列的变化， 肽影响它们被特异性T细胞识别。t细胞受体 来自T细胞的可变区结构特异于不同的肽或 DNA-肽复合物将与T细胞受体可变- 来自体外刺激抗DNA的自身免疫T细胞的区域结构 抗体生产。

Antibodies to a variety of cellular antigens, mostly nuclear in origin, have been detected in sera from mice and humans with systemic lupus erythematosus. There is compelling evidence that these autoantibodies, particularly autoantibody to DNA, are responsible at least in part for the pathological manifestations of lupus. The immunological basis for the generation of anti-DNA autoantibody in mice and humans has been difficult to elucidate. Previous attempts to stimulate antibody with the same specificity for binding to DNA as anti-DNA antibody in lupus have been unsuccessful. This fact coupled with the presence of a generalized abnormality in lymphoid cell development in mouse models for lupus has led to the proposal that lupus autoantibodies arise by antigen independent, polyclonal B cell activation. However, recent results from our molecular analyses of the structure and ontogeny of autoimmune anti-DNA antibodies have indicated that autoimmunity to DNA is both initiated and sustained as a clonally selected, specific immune response to DNA or DNA complexes. The secondary-immune characteristics of autoimmune anti-DNA antibody implicates the participation of antigen-specific helper T cells in the generation of this autoantibody, and experimental data support this hypothesis. However, little is known about the specificity and function of such T cells. We have recently established an experimental immunization model for the induction of antibody to DNA in mice not genetically predisposed to autoimmune disease. The immunogen used in this experimental system is DNA in a complex with a DNA-binding peptide. The induced anti- DNA antibody has structural and specificity characteristics identical to those of autoimmune anti-DNA antibody in lupus. Moreover, mice producing this antibody develop symptoms of early stage lupus-nephritis. The research proposed in this application will exploit the new experimental immunization system to generate T cell clones and hybrids specific for DNA-binding peptides. T cell clones and hybrids will be generated from normal, nonautoimmune-prone and autoimmune-prone mice immunized with DNA-peptide complexes. These clones and hybrids will then be used to determine the specificity and function of helper T cells that can induce in vitro anti-DNA antibody production when stimulated with specific DNA-peptide. In particular these experiments will determine whether the MHC-restricted T cell epitope for such T cells is formed by the peptide alone or a combination of DNA and peptide. The experiments will also determine how changes in the amino acid sequence of specific peptides affect their recognition by specific T cells. T-cell receptor variable-region structures from T cells specific for different peptide- or DNA-peptide complexes will be compared with T-cell receptor variable- region structures from autoimmune T cells that stimulate in vitro anti-DNA antibody production.