Immunoglobulin as a novel ligand for HLA-DM

描述（由申请方提供）：抗原呈递细胞是免疫应答的关键参与者。它们参与引发初始细胞和效应细胞，并且对于协调对感染的应答以及对自身抗原的应答（自身免疫）至关重要。在抗原呈递细胞中，B细胞独特地能够呈递少量抗原，它们通过表面免疫球蛋白（IG）捕获并摄取所述抗原。基于我们的初步发现，我们假设HLA-DM是通过使IG靠近MHC II并促进抗原从IG释放而增强B细胞表面上通过IG摄取的抗原呈递的关键参与者。在这里，我们建议评估DM/IG相互作用在细胞中的功能结果。我们将设计一个B细胞系，使其表达GAD 65特异性免疫球蛋白以及不与IG相互作用但与MHC II相互作用的突变DM。在T细胞增殖试验中，在一系列B细胞数量和抗原剂量范围内，比较突变型和野生型DM增强GAD 65呈递的能力。我们还建议使用邻近连接分析和荧光显微镜定位的网站的HLA-DM/IG相互作用的细胞。虽然我们在这里集中在表面免疫球蛋白作为B细胞中的抗原受体，我们的结果将有其他抗原呈递细胞类型的功能，如巨噬细胞和树突状细胞，采取通过表面Fc受体（FcR）的免疫复合物的影响。这些抗原/抗体复合物也靶向内体途径，在那里它们遇到HLA-DM。 公共卫生相关性：在健康状况下，免疫系统对外来抗原做出反应，并对感染做出反应。在自身免疫性疾病中，免疫系统对身体自身（自身）抗原产生反应。抗原呈递细胞通过将自身和外源抗原呈递给免疫系统的应答细胞，在有效免疫应答的发展中介导关键的起始作用。该项目研究了一种新发现的参与抗原加工和呈递的分子之间的相互作用，这一过程是塑造针对外来和自身抗原的免疫反应的关键，从而导致感染性和自身免疫性疾病。所采用的实验系统使用与人类1型糖尿病相关的蛋白质。

DESCRIPTION (provided by applicant): Antigen presenting cells are key players in the immune response. They are involved in priming naove and effector cells and are critical for orchestrating a response to infection as well as responses to self- antigens (autoimmunity). Among antigen presenting cells, B cells are uniquely capable of presenting small amounts of antigen, which they capture and take up through surface immunoglobulin (Ig). Based on our preliminary findings, we hypothesize that HLA-DM is a key player in enhancing presentation of antigen taken up through Ig on the surface of the B cell by bringing Ig in close proximity to MHC II and facilitating antigen release from Ig. Here, we propose to assess the functional outcome of the DM/Ig interaction in cells. We will engineer a B cell line to express a GAD65 specific immunoglobulin as well as a mutant DM that does not interact with Ig but does interact with MHC II. Mutant and wild type DM will be compared for their ability to enhance presentation of GAD65 in T cell proliferation assays, across a range of B cell numbers and antigen doses. We also propose to localize the site of the HLA-DM/Ig interaction in cells by using proximity ligation assays and fluorescence microscopy. Although we focus here on surface immunoglobulin as an antigen receptor in B cells, our results will have implications for the function of other antigen presenting cell types, such as macrophages and dendritic cells, that take up immune complexes via surface Fc receptors (FcR). These antigen/antibody complexes are also targeted to the endosomal pathway, where they encounter HLA-DM. PUBLIC HEALTH RELEVANCE: In health, the immune system responds to foreign antigens and mounts a response to infection. In autoimmune disease, the immune system mounts a response against the body's own (self) antigens. Antigen presenting cells mediate a critical initiating role in the development of an effective immune response by presenting self and foreign antigens to responder cells of the immune system. This project investigates a newly discovered interaction between molecules involved in antigen processing and presentation, a process that is key in shaping the immune response against foreign and self antigens with consequences for infectious as well as autoimmune diseases. The experimental system employed uses proteins of relevance to type 1 diabetes in humans.