Medical Microbiology

TheT-CellSystem 61

PresentationofEndogenousandExogenousAntigens

Fig.2. 8 Intracellularlysynthesizedendogenousantigenpeptides(leftside)are

boundtoMHCclassImoleculeswithintheendoplasmicreticulum,fixedinto

thegroovebyb 2 M,andpresentedonthecellsurface.Antigenstakenupfrom

exogenoussources(right)arecleavedintopeptideswithinphagosomes.Thepha-

gosomethenmergeswithendosomescontainingMHCclassIImolecules,the

bindingsiteofwhichhadbeenprotectedbytheso-calledCLIPfragment.These

twopresentationpathwaysfunctionallyseparateMHCclassIrestrictedCD8+Tcells

fromMHCclassIIrestrictedCD4+Tcells.

2

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Kayser, Medical Microbiology © 2005 Thieme
All rights reserved. Usage subject to terms and conditions of license.