Peptides presented by DNA-specific B lymphocytes in lupus

描述（由申请人提供）：该资助提案旨在鉴定介导T细胞帮助狼疮中双链DNA特异性B淋巴细胞的肽。系统性红斑狼疮（SLE）是一种病因不明的疾病。雌性（NZ B x NZW）F1（缩写为B/W）小鼠概括了人类狼疮患者的大多数显著特征。在这些特征中有抗dsDNA的血清抗体，其对大多数SLE患者以及所有老年B/W小鼠的临床诊断具有特异性。因此，一个重要的问题是，是什么驱动了高亲和力抗dsDNA抗体的产生？在B/W小鼠中，IgG类的高亲和力抗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小鼠中不是抗原，并且DNA不被MHC分子结合和呈递给T辅助细胞。流行的假设是DNA-蛋白质复合物如核小体介导高亲和力IgG抗体的产生。但生理性B细胞抗原的身份尚不清楚。具体地，没有已知的肽由来自任何狼疮易感小鼠模型的dsDNA特异性B细胞呈递。因此，T细胞如何帮助诱导高亲和力抗dsDNA抗体尚不清楚。为了减少自身免疫反应的复杂性，我们将利用一个经典的狼疮小鼠模型，已被修改的转基因在概念上简单的方式。它产生对（仅）dsDNA的准单克隆自身免疫应答，同时保持应答的动力学完整。与老年野生型B/W小鼠中具有不同抗原特异性的生殖中心B细胞不同， 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dsDNA特异性。我们将对生殖中心B细胞进行分类，并鉴定与其II类分子结合的肽。然后，我们将测试这些肽刺激B/W小鼠的T细胞的能力以及它们在产生抗dsDNA抗体中的功能。这将表明哪种抗原被对dsDNA具有高亲和力的B细胞的免疫球蛋白受体内化。

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.