Peptides presented by DNA-specific B lymphocytes in lupus

描述(由申请者提供)：这项资助计划旨在确定在狼疮中介导T细胞帮助dsDNA特异性B淋巴细胞的多肽。系统性红斑狼疮(SLE)是一种病因不明的疾病。雌性(NZB X NZW)F1(简称B/W)小鼠概括了人类狼疮患者的大多数显著特征。这些特征包括抗dsDNA的血清抗体，这种抗体在大多数SLE患者和所有老年B/W小鼠的临床诊断中是特异的。因此，一个重要的问题是，是什么推动了高亲和力抗dsDNA抗体的产生？在B/W小鼠中，高亲和力的抗dsDNA抗体的产生完全依赖于T辅助细胞。DsDNA本身在正常或B/W小鼠中都不是抗原，DNA不被MHC分子结合并呈递给辅助性T细胞。普遍的假设是，核小体等DNA-蛋白质复合体介导了高亲和力抗体的产生。但生理B细胞抗原的身份尚不清楚。具体地说，目前还没有已知的多肽是由任何狼疮易感小鼠模型的dsDNA特异性B细胞提供的。因此，T细胞如何帮助诱导高亲和力的抗dsDNA抗体尚不清楚。为了降低自身免疫反应的复杂性，我们将使用一个经典的狼疮小鼠模型，该模型已经通过转基因以一种概念上简单的方式进行了修改。它对dsDNA产生准单克隆性自身免疫反应，同时保持反应的动力学不变。与老年野生型B/W小鼠的生发中心B细胞不同，B细胞具有各种抗原特异性， 老年转基因小鼠的大多数B细胞具有相同的、高亲和力的单克隆性dsDNA特异性。我们将对生发中心B细胞进行分类，并洗脱和鉴定与其II类分子结合的多肽。然后，我们将测试这些多肽刺激B/W小鼠T细胞的能力，以及它们在产生抗dsDNA抗体方面的功能。这将表明哪个抗原是由与dsDNA高亲和力的B细胞的免疫球蛋白受体内化的。

DESCRIPTION (provided by applicant): This grant proposal aims to identify the peptides that mediate T cell help for dsDNA-specific B lymphocytes in lupus. Systemic lupus erythematosus (SLE) is a disease of unknown etiology. Female (NZB x NZW) F1 (abbreviated B/W) mice recapitulate most of the salient characteristics of human lupus patients. Among these characteristics are serum antibodies to dsDNA, which are specific for the clinical diagnosis in a majority of SLE patients, as well as in all older B/W mice. An important question, therefore, is what drives production of high-affinity anti-dsDNA antibody? In the B/W mouse, the generation of high-affinity anti-dsDNA antibodies of IgG class is absolutely T-helper- cell dependent. dsDNA by itself is not an antigen in either normal or B/W mice, and DNA is not bound and presented by MHC molecules to T helper cells. The prevailing hypothesis is that DNA-protein complexes such as nucleosomes mediate the generation of high-affinity IgG antibodies. But the identity of the physiological B cell antigen is unknown. Specifically, there are no peptides known that are presented by dsDNA-specific B cells from any lupus-prone mouse model. As a result, it is not known how T cells help induce high-affinity anti-dsDNA antibodies. To reduce the complexity of the autoimmune response, we will make use of a classic lupus mouse model that has been modified by transgenesis in a conceptually simple way. It yields a quasimonoclonal auto- immune response to (only) dsDNA, while leaving the kinetics of the response intact. Unlike the germinal center B cells in old wild-type B/W mice, with various antigenic specificities, the majority of the B cells of the old transgenic mice have identical and monoclonal dsDNA specificity with high affinity. We will sort the germinal center B cells, and elute and identify th peptides bound to their class II molecules. We will then test these peptides for their ability to stimulate T cells of the B/W mice and for their function in the production of anti-dsDNA antibody. This will indicate which antigen is internalized by the immunoglobulin receptor of B cells with high affinity to dsDNA.