细胞免疫T细胞活化的分子机制ppt课件.ppt

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1、T细胞活化机制1NaïveTcellsMatureTcellsthathavenotpreviouslyencounteredantigen;Preferentialmigrationtosecondarylymphoidorgans(lymphnodes),wheretheyrecognizeantigenEffectorTcellsActivatedTcellscapableofperformingthefunctionsrequiredtoeliminateforeignantigensPreferentialmigrationtositesofinfec

2、tionorinflammationShort-livedMemoryTcellsLong-lived,functionallysilentcells;MountrapidsecondaryimmuneresponsestothesameantigenexposureHeterogenous(centralandeffector)BasedonthehistoryofantigenencounterandthestageofTcellactivation.2应答诱导外周淋巴器官内抗原识别T细胞扩增和分化分化的细胞进入循环效应T细胞和其他白细胞迁移到感染部位在外周

3、效应T细胞遭遇抗原效应T细胞活化T细胞的效应功能3.ActivationofTcellschangestheexpressionofseveralcell-surfacemolecules4FunctionalresponsesofTcellsSecretionofcytokinesProliferationDifferentiationintoeffectorTcellsDifferentiationintomemoryTcells5SecretionofcytokinesOneoftheearliestdetectableresponsesofTcellst

4、oantigenrecognitionPrinciplecytokine:IL-2DistinctsetsofcytokinessecretedbyeffectorTcells6ClonalexpansionofTcells7Antigen-presentingcellsarerequiredforTcellactivation8SpecificantigenrecognitionbytheTcells;StableadhesionoftheTcellstotheAPCs;TransductionofactivatingsignalstotheTcells.Th

5、einitiationofTcellresponsestospecificantigenrequiresEachoftheseeventsismediatedbydistinctsetsofmoleculesontheTcells.9Tcellreceptorsandaccessorymolecules10Tcellreceptor(TCR)ThedefinitiveTcelllineagemarkerRecognitionofMHC-associatedpeptideantigenDualspecificityMHCrestrictionAntigenspec

6、ificityNosignal-transducingfunctions11TCRcomplexComposedofTCRandCD3protein12invariantprotein,identicalinallTcellsregardlessofspecificityresponsibleforsignaling,butnotantigenrecognitionImmunoreceptortyrosine-basedactivationmotif（ITAM)CD3Containstwocopiesofaconservedsequence:tyrosine-X

7、-X-leucine/isoleucineImportantforsignaltransductioninTcells13AntigenrecognitionandsignalingfunctionsofTcellsAntigenrecognitionSignalingfunctions14Co-receptorsCD4andCD8MatureTcellsexpresseitherCD4orCD8,butnotbothInvolvedinMHC-restrictedTcellactivationCD4ClassⅡMHCmoleculesCD8ClassⅠMH

8、CmoleculesAc