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1、T細(xì)胞活化機制1Na?veTcellsMatureTcellsthathavenotpreviouslyencounteredantigen;Preferentialmigrationtosecondarylymphoidorgans(lymphnodes),wheretheyrecognizeantigenEffectorTcellsActivatedTcellscapableofperformingthefunctionsrequiredtoeliminateforeignantigensPreferentialmigrationtositesofinfec
2、tionorinflammationShort-livedMemoryTcellsLong-lived,functionallysilentcells;MountrapidsecondaryimmuneresponsestothesameantigenexposureHeterogenous(centralandeffector)BasedonthehistoryofantigenencounterandthestageofTcellactivation.2應(yīng)答誘導(dǎo)外周淋巴器官內(nèi)抗原識別T細(xì)胞擴增和分化分化的細(xì)胞進(jìn)入循環(huán)效應(yīng)T細(xì)胞和其他白細(xì)胞遷移到感染部位在外周
3、效應(yīng)T細(xì)胞遭遇抗原效應(yīng)T細(xì)胞活化T細(xì)胞的效應(yīng)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
