1、Antigen-Presenting Cells and Antigen Presentationxiaojian WangInstitute of Immunology Zhejiang University浙江大学医学免疫学免疫11a1 nIntroduction nAntigen-presenting cellsnAntigen processing and presentationContents浙江大学医学免疫学免疫11a2I.Antigen-presenting cell,APCAntigen-presenting cells are required for T cell act
2、ivation浙江大学医学免疫学免疫11a3nA variety of cells specialized in capturing 、processing and present the antigen to the T lymphocytes,causing either tolerance or immunity.nThese cells are name as Anitgen presenting cell,APCn Dendritic cells,monocytes/macrophages and B cells are professional APCs.I.Antigen-pre
3、senting cell,APC浙江大学医学免疫学免疫11a4APC染色彩图Antigen-presenting cellsDendritic cellsMacrophagesB cells浙江大学医学免疫学免疫11a5 Non-professional APCnEndothelial cell(EC)nFibroblastic cellnActivated T cellUnder some circumstances,they can express MHC II and present Ags浙江大学医学免疫学免疫11a6II.Antigen presentation The proces
4、s by which APC express peptide-MHC on their cell surface in a form recognizable by lymphocytes.浙江大学医学免疫学免疫11a7Antigen-presenting cells浙江大学医学免疫学免疫11a8I.Dendritic cellsnhighly branched morphologyncan active naive T cellsnmarkers浙江大学医学免疫学免疫11a9The Nobel Prize in Physiology or Medicine 2011拉尔夫拉尔夫斯坦曼（斯坦曼
5、（Ralph M.Steinman）【已故已故】1943年出生于加拿大蒙特利尔，在麦吉年出生于加拿大蒙特利尔，在麦吉尔大学学习生物学和化学。之后在美国哈佛医学院学习医学，尔大学学习生物学和化学。之后在美国哈佛医学院学习医学，1968年获得医学博士学位（年获得医学博士学位（MD）。于）。于1970年被纽约洛克菲勒大学接纳，从年被纽约洛克菲勒大学接纳，从1988年起成为免疫学教授。担任该校免疫年起成为免疫学教授。担任该校免疫学与免疫性疾病中心主任。学与免疫性疾病中心主任。发现树突状细胞发现树突状细胞Dendritic cells,DC是启动适应性免疫应答是启动适应性免疫应答的关键细胞的关键细胞R.
6、M.Steinman and Z.A.Cohn.J.Exp.Med.137,11421162;1973 浙江大学医学免疫学免疫11a101.Surface markersnMHC class I/II moleculesnCD1a,CD11c,CD83(human)n33D1,NLDC145(mouse)nCo-stimulatory molecules:B7.1(CD80)/B7.2(CD86),CD40,CD44,CD54浙江大学医学免疫学免疫11a112.Sources of DC单 核 细 胞巨 噬 细 胞中 性 粒 细 胞B 细 胞T 细 胞N K 细 胞髓 系 D CBTN K髓
7、系 D C淋 巴 系 D C淋 巴 系 前 体 细 胞髓 系 前 体 细 胞多 能 造 血 干 细 胞GM-CSFTNF-aIL-4HSCMyeloid progenitorLymphoid progenitorMyeloid DC MomacrophageMyeloid DCPMNLymphoid DC浙江大学医学免疫学免疫11a123.Distribution and Classification of DCDCs are found in many organs throughout the body nDC in lymphoid tissue-Lymphoid tissue DCnI
8、nterdigitating cell,IDCnFollicular DC,FDCnthymic dendritic cell,TDCnDC not in lymphoid tissue-Non-lymphoid tissue DCnLangerhans cells nInterstitial DCnDC in body fluid-Circulating DCnVeiled cellsnPeripheral blood DC浙江大学医学免疫学免疫11a13nLocated in lymph follicles which are rich in B cells;nDerived from i
9、nterstitial DC;nHighly express FcR,CR1 and CR2;nInvolved in the generation and maintenance of memory B cells.1)Follicular DC(FDC)浙江大学医学免疫学免疫11a14Follicular DC,FDCB cellsFDCFDC express high levels of membrane receptors for antibody and complement.By these,FDC actives the B cells in lymph nodes.浙江大学医学
10、免疫学免疫11a152)Interdigitating DC(IDC)nMain APC to induce primary immune response;nDerived from Langerhans cells;nFcR-and C3bR-,MHC I and IIhigh;nDistributed mainly in the T cell area of secondary lymphoid tissue,present Ags to T cells.浙江大学医学免疫学免疫11a163)Langerhans cells(LC)nFound in the epidermis(skin)
11、and mucous membranes;nMHC I and IIhigh,highly express FcR and C3bR,Birbeck particle(due to langerin expression);nPowerful ability to capture and process Ags and migration to lymph node after activation.Langerhans IDC浙江大学医学免疫学免疫11a174.Development of myeloid DCnFour phasesnPre-DCnMonocyte,MonImmature
12、DC nUptake antigennMigrationnMature DCnExpress high levels of MHC I and II,CD80,CD86,CD40,CD54,HSP,etc.浙江大学医学免疫学免疫11a18nImmature DC Phenotype:high expression of receptors related to phagocytosis(FcR,CR,mannose receptor,DC-sign);low expression of CD54,CD40,CD80;CD86 and MHC II,CD14-Function:1)strong
13、capacity to ingest and process Ags,but weak ability to present Ags 2)induction of immune tolerance 3)sensing of infectious agents by TLR(pattern recognition receptors)浙江大学医学免疫学免疫11a19nMature DC Phenotype:low expression of receptors related to phagocytosis(FcR,CR,mannose receptor);high expression of
14、CD54,CD40,CD80,CD86 and MHC II;CD83+and CD25+Function:weak ability to capture and process Ags,powerful ability to present Ags.浙江大学医学免疫学免疫11a20 Dendritic Cell Maturation MHC II浙江大学医学免疫学免疫11a21浙江大学医学免疫学免疫11a225.DC in immune activation and immune tolerance1)DC in immune activation Present antigen and a
15、ctivate T cells The first signal MHC II-Ag:CD4+T cells MHC I-Ag:CD8+T cells The second signal co-stimulating molecules cytokines IL-12 浙江大学医学免疫学免疫11a23n Peripheral tolerance:immature DC capture autoantigen when they migrate from non-lymphoid tissue to T cell area of secondary lymphoid tissue,and ind
16、uce peripheral tolerance.nCentral tolerance:induced in negative selection of T cells in the thymus.n 2)DC induce immune tolerance浙江大学医学免疫学免疫11a24 Bone marrow Blood TissueHSCMyeloid progenitorPre-monocyteMonocyte Monocyte Macrophage II Mononuclear phagocyte system(MPS)1.Differentiation and distributi
17、on浙江大学医学免疫学免疫11a25Different names in different tissuesnMonocyte(blood)nKupffer cells(liver)nMesangial cells(kidney glomerulus)nMicroglia(brain)nAlveolar macrophages(lung)nHistiocyte(connective tissue)浙江大学医学免疫学免疫11a26nMHC-I and II molecules;nCAM:LFA-1,ICAM-1,B7,CD40;nFcR;nCR:CR1,CR3,CR4;nPattern-reco
18、gnition receptor(PRR):mannose receptor,scavenger receptor(CD91),Toll-like receptors 2.Surface markers浙江大学医学免疫学免疫11a273.Biological functions of M Antigen processing and presentation phagocytosis pinocytosis receptor-mediated endocytosis浙江大学医学免疫学免疫11a28 Antimicrobial and cytotoxic activity:a number of
19、 antimicrobial and cytotoxic substances produced by activated M can destroy phagocytosed microorganisms.Reactive oxygen intermediates,nitric oxide.浙江大学医学免疫学免疫11a29n Secretion of soluble factors:enzymes:lysozyme,myeloperoxidase,etc.cytokines:IL-1,IL-6,TNF,IL-12,IL-18,plement:C1C9,Bf coagulation facto
20、rs,PG,LTs,ACTH,etc.浙江大学医学免疫学免疫11a30phagocytosis浙江大学医学免疫学免疫11a31macrophage浙江大学医学免疫学免疫11a32浙江大学医学免疫学免疫11a33浙江大学医学免疫学免疫11a34Ag presentationM a c r o p h a g e s T a k e U p A n t ig e n M a c r o p h a g e s T a k e U p A n t ig e n I n t o V e s ic le s a n d P r e s e n t P e p t id e I n t o V e s i
21、c le s a n d P r e s e n t P e p t id e F r a g m e n t s F r o m P r o t e in sF r a g m e n t s F r o m P r o t e in sin M H Cin M H C-I II I浙江大学医学免疫学免疫11a35III.B cellsbone marrow-dependent lymphocyteAbout 5-15%of the circulating lymphoid pool are B cells defined by the presence of surface immunog
22、lobulin(Ig).浙江大学医学免疫学免疫11a36III.B cellsB C e l l s (B C R)T a k e U p A n t i g e n i n t o B C e l l s (B C R)T a k e U p A n t i g e n i n t o V e s i c l e s a n d P r e s e n t P e p t i d e V e s i c l e s a n d P r e s e n t P e p t i d e F r a g m e n t s f r o m P r o t e i n sF r a g m e n
23、t s f r o m P r o t e i n si n M H Ci n M H C-I II I浙江大学医学免疫学免疫11a37Antigen processing and presentation浙江大学医学免疫学免疫11a381.Binding and uptake of antigenndepends on the physical state of the antigen and the cell type involved.2.Antigen processingnMHC class I processing pathwaynMHC class II processing p
24、athway3.Antigen presentation浙江大学医学免疫学免疫11a391 Binding and uptake of antigennEndogenous antigens:MHCI-CD8nProduced within the cells,Such as viral proteins or tumor proteinsnprocessed by host cellnExogenous antigens:MHCII-CD4nProduced out of the cells,Bacteria,cells and soluble proteinsnprocessed by A
25、PC浙江大学医学免疫学免疫11a40浙江大学医学免疫学免疫11a41Uptake antigen by immature DC and macrophagenPinocytosis nLiquid or small granulenPhagocytosis Large molecular or microbenReceptor-mediated endocytosisneffectivenSelective浙江大学医学免疫学免疫11a42nnonspecifically engulfednBCR-mediatedUptake antigen by B cells浙江大学医学免疫学免疫11a43
26、2 Antigen processingnDegradation of externally-or internally-derived antigen into short peptide sequencesnAssociation of the peptide with MHC molecules浙江大学医学免疫学免疫11a441.The pathway of MHC I-associated endogenous Ag presentationtransported to endoplasmic reticulum by TAPdegraded by proteasome(LMP2/7)
27、in cytoplasm endogenous antigen(such as virus Ag,tumor Ag)antigen peptide（8-10 aa）Peptide/MHC-I molecule complex to surface of APC present to CD8+T kill the infected or mutated cells浙江大学医学免疫学免疫11a45Degradation in the proteasomeThe components of the proteasome include MECL-1,LMP2,LMP7.Protein in cell
28、s including non-self proteinsare degraded continuously by a multicatalytic protease of 28 subunits浙江大学医学免疫学免疫11a46Proteasome,the Cytosolic Meat Grinder That Chops Up Proteins浙江大学医学免疫学免疫11a47ENDOPLASMIC RETICULUMCYTOSOLPeptide antigens produced in the cytoplasm are physically separated from newly for
29、med MHC class INewly synthesisedMHC class I moleculesPeptides needaccess to the ER inorder to be loaded onto MHC class I moleculesLMPTAP浙江大学医学免疫学免疫11a48ER membraneLumen of ERCytosolTransporter-associated withantigen processing(TAP1&2)Transporter has preference for 8 amino acid peptideswith hydrophob
30、ic C termini.TAP-1TAP-2PeptideTAP-1TAP-2PeptideTAP-1TAP-2PeptideTAP-1TAP-2PeptideTAP-1TAP-2PeptideTAP-1TAP-2PeptideTAP-1TAP-2PeptideTAP-1TAP-2PeptideTAP-1TAP-2PeptideTAP-1TAP-2PeptideER membraneLumen of ERCytosolTAP-1TAP-2PeptideATP-binding cassette(ABC)domainHydrophobictransmembranedomainPeptide an
31、tigensfrom proteasome浙江大学医学免疫学免疫11a49Endoplasmic reticulumCalnexin bindsto nascentclass Ia chainuntil 2-M bindsTAP-1TAP-2PeptideTAP-1TAP-2PeptideTAP-1TAP-2PeptideTAP-1TAP-2PeptideTAP-1TAP-2PeptideTAP-1TAP-2PeptideTAP-1TAP-2PeptideTAP-1TAP-2PeptideTAP-1TAP-2PeptideTAP-1TAP-2PeptideTAP-1TAP-2Peptide2-
32、M binds and stabilises floppy MHCTapasin,calreticulin,TAP 1&2 form a complex with the floppy MHCCytoplasmic peptides are loaded onto the MHC molecule and the structure becomes compactMaturation and loading of MHC class I浙江大学医学免疫学免疫11a50浙江大学医学免疫学免疫11a51浙江大学医学免疫学免疫11a52浙江大学医学免疫学免疫11a532.The pathway of
33、 MHC II-associated exogenous Ag presentationExogenous antigen newly synthesised MHC class II molecule (in the endoplasmic reticulum)endosome Ii binds in the groove of MHC class II molecule lysosome protease M II C phagolysosome li CLIP protease DMDegrade into 12 15aa peptide +releasing the CLIP and
34、allowing other peptide to bind Ag peptide/MHC class II molecule complextransport to the surface of APC,recognized by CD4+TPhagocytosis,pinocytosis,FcR-phagocytosis BCR-receptor浙江大学医学免疫学免疫11a54YYPinocytosisPhagocytosisMembrane Igreceptor mediateduptakeYUptake of exogenous antigensComplement receptorm
35、ediated phagocytosisYFc receptor mediated phagocytosisopsonization浙江大学医学免疫学免疫11a55Proteases produce 24 amino acid long peptides from antigensEndosomesExogenous pathwayIncreasein acidityCell surfaceTo lysosomesUptakeProtein antigensIn endosomeCathepsin B,D and L proteases are activated by the decreas
36、e in pH浙江大学医学免疫学免疫11a56Need to prevent newly synthesised,unfolded self proteins from binding to immature MHC Invariant chain stabilises MHC class II by non-covalently binding to the immature MHC class II molecule and forming a nonomeric complexIn the endoplasmic reticulumMHC class II maturation and
37、invariant chain浙江大学医学免疫学免疫11a57 involve in the assembling and folding of MHC class II molecule;Block the groove of MHC class II molecule;Lead the assembled class II molecule to M II C.The functions of Ii:CLIP：class II-associated invariant chain peptide浙江大学医学免疫学免疫11a58HLA-DM catalyses the removal of
38、CLIPMIIC compartmentHLA-DMReplaces CLIP with a peptide antigen using a catalytic mechanism(i.e.efficient at sub-stoichiometric levels)Discovered using mutant cell lines that failed to present antigenHLA-DO may also play a role in peptide exchangeSequence in cytoplasmic tail retains HLA-DM in endosom
39、esHLA-DMHLA-DR浙江大学医学免疫学免疫11a59MIIC compartment sorts peptide-MHC complexes for surface expression orlysosomal degradationSurface expression of MHC class II-peptide complexesExported to the cell surfaceSent to lysosomes for degradation 浙江大学医学免疫学免疫11a60浙江大学医学免疫学免疫11a61浙江大学医学免疫学免疫11a62浙江大学医学免疫学免疫11a63I
40、mportant aspects of Ag processingnLocation of pathogen dictates type of responseVirus in cytosol MHC class I pathway CTLExtracellular pathogen MHC class II pathway CD4 response Ab production cytokine production 浙江大学医学免疫学免疫11a64Sample question1.Products of TAP-1 and TAP-2 genesA.Bind 2m.B.Prevent pep
41、tide binding to MHC molecules.C.Are part of the proteasome.D.Transport peptides into the endoplasmic reticulum for binding to MHC class I.E.Transport peptides into endoplasmic reticulum for binding to MHC class II.Answer=D浙江大学医学免疫学免疫11a652.Which of the following cells is professional antigen-present
42、ing cell?-()A.Dendritic cellsB.Endothelial cellsC.NeutrophilsD.T cellsE.Mast cellsAnswer=A浙江大学医学免疫学免疫11a663.Which of the following gene products is involved in the pathway of MHC class I associate endogenous antigen presentation?()A.LMP2/7B.IiC.HLA-DMD.HLA-DOE.HLA-DR3Answer=A浙江大学医学免疫学免疫11a67Review questionsnWhat are the differences between immature DC and mature DC?nDescribe the pathway of MHC I-associated endogenous Ag presentation and MHC II-associated exogenous Ag presentation.浙江大学医学免疫学免疫11a68Thanks for your attention!浙江大学医学免疫学免疫11a69
