抗原的加工與呈遞ppt課件(完整版)
【正文】 dosomes by invariant chain Cathepsin L degrades Invariant chain CLIP blocks groove in MHC molecule MHC Class II containing vesicles fuse with antigen containing vesicles Removal of CLIP ? How can the peptide stably bind to a floppy binding site? Competition between large number of peptides HLADM catalyses the removal of CLIP MIIC partment HLADM Replaces CLIP with a peptide antigen using a catalytic mechanism Sequence in cytoplasmic tail retains HLADM in endosomes HLADM HLADR Conception ? MⅡ C – MHC class Ⅱ partment， MHCⅡ 類分子區(qū)室 – 富含外源性抗原肽、 MHCⅡ 類分子、 HLADM的低 pH值的晚期內(nèi)體 – MHCⅡ 類分子荷肽主要場所 ? HLADM的編選作用 – HLADM可驅(qū)逐與 Ⅱ 類分子抗原結(jié)合槽低親和 力結(jié)合的肽，直至有高親和力的肽與Ⅱ 類分 子結(jié)合，才與 Ⅱ 類分子分離，使其抗原結(jié)合 槽恢復(fù)閉合狀態(tài)。 遞呈給 CD4+T細(xì)胞 ? Presentation of exogenous antigen – Ag肽 Ⅱ 類分子經(jīng)胞吐作用表達(dá)于 APC表面 – 供 CD4+T細(xì)胞識(shí)別 MIIC partment sorts peptideMHC plexes for surface expression or lysosomal degradation Surface expression of MHC class II peptide plexes Exported to the cell surface Sent to lysosomes for degradation 二、內(nèi)源性抗原加工遞呈途徑 ? Endogenous processing and presentation pathway ? MHC class Ⅰ pathway 內(nèi)源性 Ag加工后由 MHCⅠ 類分子遞呈 階段： ? 內(nèi)源性 Ag肽的產(chǎn)生及轉(zhuǎn)運(yùn) ? MHCⅠ 類分子荷肽 ? 遞呈給 CD8+T細(xì)胞 MHCⅠ 類途徑 內(nèi)源性抗原肽的產(chǎn)生 ? Generation of endogenous antigenic peptide – 內(nèi)源性抗原泛素化 – 經(jīng)蛋白酶體（ LMP）降解為短肽 Crystal Structure Of The 20s Proteasome From Yeast View End on Degradation in the proteasome These ponents are induced by IFNγ and replace constitutive ponents to confer proteolytic properties The ponents of the proteasome include MECL1, LMP2, LMP7 LMP2 amp。 Presentation T cells do not recognise native antigens Y B Y Y Y Y Y Y Y B Y T Y T Proliferation and antibody production No proliferation No cytokine release Crosslinking of surface membrane Ig Y B Y B Y B Y B Y B Y B Y B Cell surface peptides of Ag Antigens must be processed in order to be recognised by T cells Y T T cell respons
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