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chapter8Theresultsoftheseexperiments,outlinedinFigure8-1,showedthatstrain-2antigen-pulsedmacrophagesactivatedstrain-2andF1Tcellsbutnotstrain-13Tcells.Similarly,strain-13antigen-pulsedmacrophagesactivatedstrain-13andF1Tcellsbutnotstrain-2Tcells.Subsequently,congenicandrecombinantcongenicstrainsofmice,whichdifferedfromeachotheronlyinselectedregionsoftheH-2complex,wereusedasthesourceofmacrophagesandTcells.Theseex-perimentsconfirmedthattheCD4�THcellisactivatedandproliferatesonlyinthepresenceofantigen-pulsedmacrophagesthatshareclassIIMHCalleles.Thus,antigenrecognitionbytheCD4�THcellisclassIIMHCrestricted.In1974R.ZinkernagelandP.Dohertydemonstratedtheself-MHCrestrictionofCD8�Tcells.Intheirexperiments,micewereimmunizedwithlymphocyticchoriomeningitis(LCM)virus;severaldayslater,theanimals’spleencells,whichincludedTCcellsspecificforthevirus,wereisolatedandincubatedwithLCM-infectedtargetcellsofthesameordifferenthaplotype(Figure8-2).TheyfoundthattheTCcellskilledonlysyngeneicvirus-infectedtargetcells.LaterstudieswithcongenicandrecombinantcongenicstrainsshowedISelf-MHCRestrictionofTCellsIRoleofAntigen-PresentingCellsIEvidenceforTwoProcessingandPresentationPathwaysIEndogenousAntigens:TheCytosolicPathwayIExogenousAntigens:TheEndocyticPathwayIPresentationofNonpeptideAntigensAntigenProcessingandPresentationRaTcellrequiresthatpeptidesderivedfromtheantigenbedisplayedwithinthecleftofanMHCmoleculeonthemembraneofacell.Theformationofthesepeptide-MHCcomplexesrequiresthataproteinantigenbedegradedintopeptidesbyasequenceofeventscalledanti-genprocessing.ThedegradedpeptidesthenassociatewithMHCmoleculeswithinthecellinterior,andthepeptide-MHCcomplexesaretransportedtothemembrane,wheretheyaredisplayed(antigenpresentation).ClassIandclassIIMHCmoleculesassociatewithpep-tidesthathavebeenprocessedindifferentintracellularcom-partments.ClassIMHCmoleculesbindpeptidesderivedfromendogenousantigensthathavebeenprocessedwithinthecytop...