【正文】 e No T cell response No T cell response No T cell response No T cell response Soluble native Ag Cell surface native Ag Soluble peptides of Ag Cell surface peptides of Ag presented by cells that express MHC antigens ANTIGEN PROCESSING Y T MHC directs the response of T cells to foreign antigens Y T Ag Y T Ag Anti response No anti response MHC antigens PRESENT foreign antigens to T cells Cells that present antigen are ANTIGEN PRESENTING CELLS Y T Y T Y T Y T Y Blocking antiMHC antibody Y Y Y Ag B細胞 漿細胞 Ab APC Th細胞 Ag肽 MHC分子 T細胞 Tc細胞 Contents ?抗原遞呈細胞 ?抗原加工遞呈途徑 第一節(jié) 抗原遞呈細胞 Antigen Presenting Cells ? 基本概念 ? 抗原遞呈細胞 一、基本概念 ? 抗原加工與遞呈 （ Antigen processing and presentation） – 抗原加工是指蛋白質抗原在細胞內被降解成能與 MHC結合的肽的過程。 2 form a plex with the floppy MHC Cytoplasmic peptides are loaded onto the MHC molecule and the structure bees pact Maturation and loading of MHC class I 遞呈給 CD8+T細胞 ? Presentation of endogenous antigen – Ag肽 MHCⅠ 類分子經高爾基體 – 通過胞吐作用表達于細胞表面 – 供 CD8＋ T細胞識別 Fate of MHC class I Sent to lysosomes for degradation Exported to the cell surface Endoplasmic reticulum Peptide Peptide HSV protein blocks transport of viral peptides into ER Sent to lysosomes for degradation Evasion of immunity by interference with endogenous antigen processing Sent to lysosomes for degradation Normally exported to the cell surface Adenoviral protein retains MHC class I in the ER Evasion of immunity by interference with endogenous antigen processing 三、非經典抗原加工遞呈途徑 ? Non classical pathway ? 外源性抗原也可被 MHCⅠ 類分子遞呈 – 外源性抗原穿透細胞膜進入胞漿 – 外源性抗原自內體逸出進入胞漿 以內源性抗原方式加工遞呈給 CD8+T細胞 ? 內源性抗原也可被 MHCⅡ 類分子遞呈 – 胞質內蛋白形成自吞小泡，與內體 /溶酶體融合 以外源性抗原方式加工遞呈給 CD4+T細胞 ? 交叉致敏（ crosspriming） – 專職性 APC 激活未致敏的腫瘤或病毒抗原特異性 CD8+T細胞的機制 – DC具有交叉致敏作用 學習了抗原提呈細胞的特性和功能后， 你是如何體會抗原提呈細胞的免疫學功能和生物學意義的呢？