细胞免疫.pptVIP

教学大纲T淋巴细胞对抗原的识别及免疫应答 一、目的和要求 （一）掌握T淋巴细胞对抗原的识别；T淋巴细胞活化的信号要求；效应性T淋巴细胞的作用 （二）了解T淋巴细胞活化的信号转导途径。 二、教学内容 （一）T淋巴细胞对抗原的识别 （二）T细胞的活化过程 （三）效应性T淋巴细胞的应答效应 第一节 T细胞对抗原的识别 一、APC向T细胞提呈抗原的过程 二、APC与T细胞的相互作用 T细胞与APC非特异性的结合 粘附分子 T细胞与APC特异性的结合 TCR,CD4/CD8 免疫突触（T细胞突触） 是指在T细胞和抗原提呈细胞识别结合的过程中，多种跨膜分子聚集在富含神经鞘磷脂和胆固醇的“脂筏”上，并相互靠拢成簇，形成细胞间相互作用的部位，在免疫突触形成的后期，其中心区为TCR-pMHC、辅助受体、协同刺激分子，周围分布着粘附分子等。 第二节 T细胞活化的过程 第一信号 第二信号 二、T细胞活化的信号转导途径 T细胞活化的信号转导：T淋巴细胞受体是由多肽链组成的跨膜蛋白复合体，他的胞外部分可识别特异性抗原太，但胞内部分较短，要借助CD3分子及CD4/CD8分子及CD28等分子的辅助，才能将胞外刺激信号传递到细胞内，使转录因子活化，转位到核内，活化相关基因。 三、T细胞活化信号涉及的靶基因 转录因子 效应 IL-2基因的调节是T细胞活化期间细胞因子转录调节的原型 T细胞 CD4+T CD8+T 记忆T细胞的形成 CD45RA- CD45RO+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Cross presentation for CD8 priming Problem: how can na?ve CD8 cells get activated if activation requires peptide/MHC class I plus costimulation? This would require that professional antigen presenting cells get infected with virus, for example. A second problem is that viruses that manage to suppress MHC class I would evade detection. Cross presentation of exogenous proteins on MHC class I can be specifically carried out by dendritic cells. There is an important exception to the notion that class I MHC molecules present peptides generated within the cytoplasm. What if the virus doesn’t infect macrophages or dendritic cells? How do viral peptides get presented by professional antigen presenting cells so that an immune response can be induced? The answer is that dendritic cells, but not other cells, have a specialized mechanism for shuttling peptides taken up by endocytosis or phagocytosis into the MHC class I pathway. Dendritic cell cross presentation of ingested antigens on MHC class I Cross presentation = Dendritic cell, but not other cells, can take up antigens and shuttle them into the class I pathway. This is most efficient when the antigens are particulate Provides a mechanism to get viral and bacterial antigens into profession