Characterization of anergic human B cells

描述（由申请人提供）：据估计，多达75%的新产生的B细胞是自身反应性的。三种互补机制防止这些自身反应性细胞引起自身免疫;克隆缺失，受体编辑和无反应性。我们最近发现，高达50%的未成熟B细胞注定会变得无反应性。因此，无反应性可使大多数自身反应性B细胞沉默。与主要发生在未成熟骨髓B细胞中的克隆缺失和编辑不同，无反应性可发生在外周B细胞中并且是可逆的。因此，无反应性在生理学上对于通过体细胞突变沉默在生殖中心产生的自身反应性B细胞可能特别重要。无反应性的抑制或逃避将使这些B细胞参与自身免疫。直到最近，还不可能在生理（非转基因）环境中研究无反应性细胞的频率和/或生物学。这导致了对无反应性的生理意义的怀疑。我们最近定义了一个标记集，可以从正常库中识别、分离和研究无反应性B细胞，并将我们的研究扩展到人类。使用这些工具，我们建议解决的假设，即无反应性B细胞产生的体细胞突变的生殖中心，以及从自身反应性生殖系特异性。我们推测，人类自身反应性细胞的高频率产生决定了在该物种中必须存在显著的无反应性B细胞群体。我们将回答两个具体问题。目的1：野生型小鼠中无反应性B细胞的来源是什么？拟定的实验将确定小鼠中因无反应性而沉默的自身抗体特异性或亲和力是否存在偏倚，并定量该群体中携带体细胞突变受体的细胞频率。AIM 2：什么标志物定义了人类的无反应性B细胞？我们还将确定该人群中体细胞突变受体的频率以及导致人类无反应性的自身抗体的特异性和亲和力。相关性：自身抗体是许多自身免疫性疾病的特征。无反应性是阻止B细胞成为有效的抗原呈递细胞和产生自身抗体的机制之一。这项工作将使我们能够识别人类的无反应性细胞，并进一步了解导致B细胞无反应性的条件。

DESCRIPTION (provided by applicant): It has been estimated that as many as 75% of newly produced B cells are autoreactive. Three complementary mechanisms prevent these autoreactive cells from causing autoimmunity; clonal deletion, receptor editing, and anergy. We have recently shown that up to 50% of immature B cells are destined to become anergic. Thus anergy may silence the majority of autoreactive B cells. Unlike clonal deletion and editing, which occur primarily in immature bone marrow B cells, anergy can occur in peripheral B cells and is reversible. Therefore, anergy may be particularly important physiologically for silencing autoreactive B cells generated in germinal centers by somatic mutation. Reversal or escape from anergy would allow such B cells to participate in autoimmunity. Until recently it has not been possible to study the frequency and/or biology of anergic cells in a physiologic (nontransgenic) setting. This has led to skepticism regarding the physiologic significance of anergy. We have recently defined a marker set that allows identification, isolation, and study of anergic B cells from a normal repertoire, and extension of our studies to humans. Using these tools we propose to address the hypothesis that anergic B cells arise by somatic mutation in germinal centers as well as from autoreactive germline specificities. We hypothesize that the high frequency production of autoreactive cells in humans dictates that a significant population of anergic B cells must exist in this species. We will address two specific questions. AIM 1: What are the origins of anergic B cells in wildtype mice? Proposed experiments will determine if there is a bias in the autoantibody specificities or affinities that are silenced by anergy in mice and quantitiate the frequency of cells bearing somatically mutated receptors in this population. AIM2: What markers define anergic B cells in humans? We will also determine the frequency of somatically mutated receptor in this population and the specificities and affinities of autoantibodies that lead to anergy in humans. Relevance: Autoantibodies are characteristic of many autoimmune diseases. Anergy is one mechanism by which B cells are prevented frombecoming effective antigen presenting cells and producing autoantibodies. This work will allow us to identify anergic cells in humans and further our understanding of the conditions which lead to B cell anergy.