apc抗原提呈细胞及抗原提呈.ppt

三种APC细胞特征比较 2020/11/3 * 概念 抗原递呈细胞 抗原递呈 -胞质溶胶途径(MHC-I类分子途径) -溶酶体途径(MHC-II类分子途径) -CD1分子递呈途径 主 要 内 容 2020/11/3 * 抗 原 处 理（antigen processing) APC细胞将胞浆内自身产生或摄入胞内的抗原消化降解成一定大小的抗原肽片段，以便与胞内MHC分子结合。 2020/11/3 * Y The site of pathogen replication or mechanism of antigen uptake determines the antigen processing pathway used Y Cytosolic compartment Endogenous processing (Viral antigens) Vesicular Compartment Contiguous with extracellular fluid Exogenous processing (Streptococcal, Mycobacterial antigens) Distinct mechanisms of antigen generation are used to raise T cells suited to the elimination of endogenous or exogenous pathogens INTRACELLULAR REPLICATION EXTRACELLULAR OR ENDOSOMAL REPLICATION 2020/11/3 * 递呈抗原的来源 * 外源性抗原(exogenous antigen)： 来源于APC外的抗原，通过溶酶体途径由MHCII类分子递呈给CD4+T细胞。 * 内源性抗原(endogenous antigen)： 细胞内合成的抗原，通过胞质溶胶途径由MHCI类分子递呈给CD8+T细胞。 2020/11/3 * Pathogens in Cytosol/Vesicles 2020/11/3 * 概念 抗原递呈细胞 抗原递呈 -胞质溶胶途径 -溶酶体途径 -CD1分子递呈途径 主 要 内 容 2020/11/3 * 胞质溶胶（MHC-I类分子途径） 内源性抗原被胞质溶胶中蛋白酶体降解为小分子抗原肽后，与 MHC-I类分子结合，形成抗原肽/ MHC-I类分子复合物，供CD8+T细胞识别的过程。如病毒抗原、肿瘤抗原，组织抗原等主要经此途径递呈。 2020/11/3 * Degradation in the proteasome The components of the proteasome include MECL-1, LMP2, LMP7 These components are induced by IFN-? and replace constitutive components to confer proteolytic properties. LMP2 7 encoded in the MHC Proteasome cleaves proteins after hydrophobic and basic amino acids and releases peptides into the cytoplasm Cytoplasmic cellular proteins, including non-self proteins are degraded continuously by a multicatalytic protease of 28 subunits 2020/11/3 * Proteasome, the Cytosolic Meat Grinder That Chops Up Proteins 2020/11/3 * Crystal Structure Of The 20s Proteasome From Yeast View End on 2020/11/3 * ENDOPLASMIC RETICULUM CYTOSOL Peptide antigens produced in the cytoplasm are physically separated from newly formed MHC class I Newly synthesised MHC class I molecules Peptides need access to the ER in order to be loaded onto MHC class I mole