ANTIGEN RECOGNITION BY THE GAMMA DELTA T CELL RECEPTOR

GAMMA Delta T 细胞受体对抗原的识别

• 批准号: 2068209
• 负责人: ELWYN Y LOH
• 金额: $ 12.02万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-09-01 至 1997-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2068209
• 关键词: T cell receptor; T lymphocyte; antigen presentation; clone cells; gene mutation; leukocyte activation /transformation; lymphocyte proliferation; polymerase chain reaction; protein sequence; receptor binding; receptor expression; site directed mutagenesis; staphylococcal enterotoxin; superantigens; tetanus toxin; transfection

In man, there have been many descriptions of diseases where gammadelta T cells may play a role. there have been increased numbers of gammadelta T cells associated with infectious diseases such as tuberculosis, with diseases of autoimmune etiology such as rheumatoid arthritis, and with malignant disease. Many antigens have been described for gammadelta T cells, including mycobacterial proteins, heatshock proteins, staphylococcal endotoxin A (SEA), and a cell surface molecule on Daudi leukemia cells. the long term objective of this proposal is to understand how the gammadelta T cell recognizes antigen, a function that is thought to be performed by the gammadelta T cell receptor (TCR). It has been hypothesized that this receptor will interact with antigen in the same way that the alphabeta T cell receptor interacts with its ligands. For this study, a series of human gammadelta T cell clones has been isolated that recognize tetanus toxin (TTn), possibly in the context of MHC. Some of these clones can also specifically recognize other antigens including the Daudi leukemia cell line. the cDNAs coding for the TCR have been isolated and expressed in a host T cell that does not express an endogenous TCR. This study will use these transfectants to analyze in molecular detail the requirements of the gammadelta TCR to recognize a bacterial protein antigen and apparent superantigens: 1) Establish that specificity for tetanus and for superantigens can be transferred by the adoptive receptor. The transfectants will be stimulated with antigen, and the IL-2 response will be measured. Controls will include alphabeta transfectants specific for TTn and gammadelta transfectants from non-responding cells. 2) Determine the epitopes of tetanus toxin that are recognized by gammadelta TCR. By comparing the response to antigen on fixed versus unfixed antigen presenting cells, the need for antigen processing of TTn will be determined. If gammadelta receptors recognize TTn as a peptide, a series of TTn peptides produced in bacteria will be tested to find a minimal antigen recognized by the receptor. 3. Determine the functional requirements of the CDR of the gammadelta TCR for antigen recognition of tetanus toxin. Models of the alphabeta TCR based on homology with immunoglobulin structures have led to the proposal that CDR1 (CDR- complementarity determining region) and CDR2 recognize MHC while CDR3 recognizes peptide. The model predicts that antigen specificity can be transferred by transferring the CDRs from one receptor to another. Mutations of this type will be used to test the hypothesis on the gammadelta TCR. 4) Establish the regions of the gammadelta receptor that are necessary for binding antigens that appear to be recognized as superantigens. Superantigens can be recognized by alphabeta TCR in a way different from the recognition of peptides. the regions of the gammadelta TCR that are responsible for the recognition of apparent superantigens will be determined with adoptive receptors that have selective mutations. These studies on the recognition properties of the gammadelta T cell receptor will clarify how the gammadelta T cell recognizes antigen and will provide a system where disease associated gammadelta T cells and antigens can be studied in the future.

在人类中，有许多关于 γδT 导致的疾病的描述。 细胞可能发挥作用。 伽玛δT的数量有所增加 与结核病等传染病相关的细胞 自身免疫性疾病，例如类风湿性关节炎，以及 恶性疾病。 已描述了许多针对 γδT 的抗原 细胞，包括分枝杆菌蛋白、热休克蛋白、葡萄球菌蛋白 内毒素 A (SEA) 和 Daudi 白血病细胞上的细胞表面分子。 该提案的长期目标是了解如何 γδ T 细胞识别抗原，这一功能被认为是 由γδT细胞受体（TCR）执行。 它一直 假设该受体将以相同的方式与抗原相互作用 Alphata T 细胞受体与其配体相互作用。 为了这 研究中分离出一系列人类 γδ T 细胞克隆 可能在 MHC 的背景下识别破伤风毒素 (TTn)。 一些 这些克隆还可以特异性识别其他抗原，包括 Daudi白血病细胞系。 编码 TCR 的 cDNA 已被分离 并在不表达内源 TCR 的宿主 T 细胞中表达。 本研究将使用这些转染子对分子细节进行分析 gammadelta TCR 识别细菌蛋白抗原的要求 和表观超抗原： 1) 确定破伤风和表观超抗原的特异性 因为超抗原可以通过过继受体转移。 这 转染子将受到抗原刺激，IL-2 反应将 被测量。 对照将包括特定于 来自无反应细胞的 TTn 和 gammadelta 转染子。 2）确定 γδ TCR 识别的破伤风毒素表位。 经过 比较固定抗原与未固定抗原的抗原反应 呈递细胞，需要对 TTn 进行抗原加工 决定。 如果 gammadelta 受体将 TTn 识别为肽，则一系列 将测试细菌中产生的 TTn 肽，以找到最小的 被受体识别的抗原。 3.确定功能 γδ TCR 的 CDR 对抗原识别的要求 破伤风毒素。 基于同源性的 Alphata TCR 模型 免疫球蛋白结构导致了这样的提议：CDR1 (CDR- 互补决定区）和 CDR2 识别 MHC，而 CDR3 识别肽。 该模型预测抗原特异性可以 通过将 CDR 从一种受体转移到另一种受体来转移。 这种类型的突变将用于检验关于 γδ TCR。 4) 建立γδ受体区域 对于结合似乎被识别为的抗原是必需的 超抗原。 Alphabeta TCR 可以通过某种方式识别超级抗原 与肽的识别不同。 伽玛三角洲地区 负责识别表观超抗原的 TCR 将 通过具有选择性突变的过继受体来确定。 这些 γδT细胞受体识别特性的研究 将阐明 gammadelta T 细胞如何识别抗原并将提供 一个可以与疾病相关的 γδ T 细胞和抗原的系统 将来学习。