apc抗原提呈细胞及抗原提呈 ppt课件.ppt

* 溶 酶 体 途 径 外源性抗原 新合成的MHC-II类分子 （内质网中） 吞噬小体 li占据抗原结合槽 溶酶体 蛋白酶 MIIC 吞噬溶酶体 li CLIP 蛋白酶作用 DM 降解成13?18AA小肽 + CLIP脱落,暴露抗原结合槽 抗原肽/MHC II类分子复合物 转运至APC表面,供CD4+T细胞识别 吞噬、内吞、吞饮 Menu F B MHC对抗原的交叉提呈 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 CD1分子递呈途径 1. CD1的特征 分五型：CD1A、B、C、D、E, 与b2m组成二聚体； 与MHCI/II类分子有30%同源性，无多态性； CD1表达于专职APC表面，还可存在于内体/溶酶体腔室中，酸性环境改变其构象，与抗原结合。 2. 抗原递呈特征 主要递呈糖脂或脂类抗原，特别是分支杆菌的某些成分； 递呈给CD4+T、CD8+T、CD4-CD8-T、NK1.1T细胞。 脂类抗原的CD1分子提呈途径 抗原递呈的三条途径 小 结 MPS的生物学功能。 成熟与未成熟DC的生物学特征及DC的生物学功能。 试述胞质溶胶抗原递呈途径的过程。 试述溶酶体抗原递呈途径的过程。 * * 三类分子、三类细胞、九大行为 * The only known function of dendritic cells is to present antigen to naive T cells and activate them. As we know, dendritic cells arise from bone marrow progenitors and migrate via the blood to peripheral tissues and organs. The immature DC in the peripheral tissues are highly phagocytic via receptors such as DEC 205 and are actively macropinocytic but express low levels of MHC proteins, and they lack co-stimulatory B7 molecules. So, they cannot present antigen and they are not yet equipped to stimulate naive T cells. In contrast, the mature DC in lymphoid tissue have high ability to present antigen but are no longer phagocytic. They express B7.1, B7.2, and high levels of MHC class I and class II molecules, as well as high levels of the adhesion molecules ICAM-1, ICAM-2, LFA-1, and LFA-3 (center panel). They also express high levels of the dendritic-cell-specific adhesion molecule DC-SIGN, which binds ICAM-3 with high affinity. * DC通过FcR和C3bR吞噬被抗体和补体包被的抗原；通过甘露糖受体吞噬甘露糖化的抗原，受体介导的内吞句有选择性、高效性和饱和性。 DC非特异性吞噬颗粒抗原能力很弱。 FDC表面捕获抗原，无吞噬处理功能，直接提呈给B细胞识别 * * 分泌功能： -产生溶酶体酶、髓过氧化物