Tolerance in Polyclonal and Oligoclonal Immune Systems

描述(由申请人提供)：等位基因和等型(单倍型)排除证实每个B细胞只表达一对免疫球蛋白重链和轻链，因此表现出单一的特异性。然而，在健康人和野生型小鼠中，表达两条重链或两条轻链(单倍型)的B细胞的频率估计约占B细胞总数的2%-10%。对免疫球蛋白转基因小鼠的分析表明，自身反应性B细胞有时可以通过共表达非自身反应性抗原受体来绕过中枢耐受机制。这些单倍型细胞共表达自身反应性和非自身反应性抗原受体，并在成熟的B细胞群体中发现。由于大多数初级免疫球蛋白基因重排编码自身反应的特异性，我们认为野生型单倍型B细胞比单倍型B细胞(单抗表达)具有更高的自身反应性。这项建议的目的是了解小鼠中单倍型B细胞的性质和调节，并确定这些细胞是否与自身免疫有关。为了实现这一点，我们概述了三个特定的目标，它们将表征具有野生型抗体谱系的小鼠中双重免疫球蛋白轻链表达的B细胞，确定这些B细胞是否有助于自身免疫倾向小鼠的自身免疫过程，并了解单倍型B细胞是如何被生理调节的。包括单倍型的自身反应性B细胞将在体外和体内使用各种小鼠模型和各种技术进行评估，其中包括B细胞杂交瘤的产生和特征以及细胞过继转移的使用。由于自身免疫是一个重要的健康问题，具有多种迄今尚不清楚的病因学基础，因此有必要对包含单倍型的B淋巴细胞进行分子和细胞分析。特别是，我们预测单倍型B细胞是独一无二的，因为它们表达的自身抗体具有与自身抗原高度亲和力相互作用的潜力，并产生同时结合异源抗原和自身抗原的抗体。 项目简介：系统性自身免疫性疾病，如红斑狼疮和类风湿性关节炎，是由B细胞和其他血细胞类型缺陷引起的复杂疾病，继续导致显著的发病率和死亡率。虽然对这些疾病已经有了重要的认识，但要完全了解这些疾病的病因和发病机制，仍有大量的工作要做。自身免疫中的一些B细胞会分泌与机体产生的分子相结合的自身抗体。目前还不清楚为什么会产生这些细胞，为什么它们会被激活来分泌自身抗体。我们的研究旨在确定小鼠中一小部分表达两种抗体的B细胞的特征，以确定这些细胞是否是自身抗体分泌细胞的祖细胞和自身免疫的致病因子。

DESCRIPTION (provided by applicant): Allelic and isotypic (haplotype) exclusion establishes that each B cell expresses only one immunoglobulin heavy and light chain pair and, consequently, exhibits a single specificity. Nevertheless, B cells expressing either two heavy or two light chains (haplotype-included) exist in healthy individuals and wild-type mice at a frequency estimated to be approximately 2-10% of the B cell population. Analyses of immunoglobulin transgenic mice have demonstrated that autoreactive B cells can sometimes bypass mechanisms of central tolerance by co-expressing non-autoreactive antigen receptors. These haplotype-included cells co-express autoreactive and non-autoreactive antigen receptors and are found in the mature B cell population. Because the majority of primary immunoglobulin gene rearrangements encode autoreactive specificities, we propose that wild-type haplotype-included B cells have higher chances of being autoreactive than haplotype-included (single Ab-expressing) B cells. The goal of this proposal is to understand the nature and regulation of haplotype-included B cells in mice and to determine if these cells are associated with autoimmunity. To accomplish this we outline three Specific Aims that will characterize dual immunoglobulin light chain- expressing B cells in mice with a wild-type antibody repertoire, determine whether these B cells contribute to the autoimmune process of autoimmune-prone mice, and understand how haplotype- included B cells are physiologically regulated. Haplotype-included autoreactive B cells will be evaluated both in vitro and in vivo using various mouse models and a variety of techniques that include the generation and characterization of B cell hybridomas and the use of cell adoptive transfer. Because autoimmunity is a significant health issue that has multiple, as of yet, poorly understood etiological bases, a molecular and cellular analysis of haplotype-included B lymphocytes is warranted. In particular, we predict haplotype-included B cells to be unique in that the autoantibody they express have the potential to exhibit a high avidity interaction with autoantigen and produce antibodies that simultaneously bind foreign as well as self-antigens. Project Narrative: Systemic autoimmune diseases such as lupus erythematosus and rheumatoid arthritis are complex disorders caused by defects in B and other blood cell types and that continue to cause significant morbidity and mortality. Although significant knowledge on these conditions has been achieved, substantial work remains to be done to fully understand the etiology and pathogenesis of these diseases. Some B cells in autoimmunity secrete autoantibodies that bind to molecules produced by the organism. It is still vastly unclear why these cells are generated and why they are activated to secrete autoantibodies. Our studies aim at characterizing a small population of B cells in mice that express two types of antibodies to determine whether these cells are progenitors of autoantibody-secreting cells and pathogenic players of autoimmunity.