Medical Microbiology

combinationresultinginarearrangementofthesesegments,suchthat oneVH,oneDH,andoneJHsegmentbecomecombined.Thusthegerm linedoesnotco ...

TheB-CellSystem 55 RearrangementoftheB-andT-CellReceptorGenes 2 All rights reserved. Usage subject to terms and conditions of li ...

regionsencodingtheHchainsegmentsCl,Cd,Cc,Ca,andCe,inconsecutive order.ThusallimmunoglobulinproductionbeginswiththesynthesisofIgM ...

TheT-CellSystem T-CellReceptors(TCR)andAccessoryMolecules LikeBcells,Tcellshavereceptorsthatbindspecificallytotheirstericcounter ...

chainsofIgbearingthesamedesignations).Bothchainshavetwoextracel- lulardomains,atransmembraneanchorelementandashortintracellulare ...

immunologicalrejectionofcelltransfusionsortissueandorgantransplants. Itstruefunctionasapeptide-presentingmoleculewasnotdiscovere ...

FunctionsofMHCmolecules.MHCclassIandIImoleculesfunctionmainlyas moleculescapableofpresentingpeptides(Figs.2. 7 –2. 9 ).Thesetwoc ...

TheT-CellSystem 61 PresentationofEndogenousandExogenousAntigens Fig.2. 8 Intracellularlysynthesizedendogenousantigenpeptides(lef ...

length.ThegrooveofMHCclassIImoleculesisopen-ended,andcancontain peptidesof 9 – 15 (usually 10 – 1 2)aminoacidsinlength. Tcellsca ...

&Blymphocytes—theseserveasatypeofAPCforThelpercellsduringT-B collaborations. TheconsequencesofMHCvariation.Becauseeveryindiv ...

thymushadbeenremoved(andwhichthereforehadnoTcells).Implantation ofanewthymuswithMHCclassImoleculesoftypea(MHCclassIa)intothe MHC ...

effectorfunction.However,cytotoxicityisonlyoneofseveralimportantfunc- tionsexpressedbyCD8+Tcells.Theyalsohavemanyothernon-lyticf ...

bythedirecteliminationofAPC(i.e.,bychangingtheantigenkinetics),or indirectlyviacytokineeffects(seeFig.2. 14 ,p.78).Thus,thenames ...

structurecontainingidenticalandrepetitivelyarrangeddeterminants—isa highly efficientandTcell-independent processwhich involves d ...

&Type 1 T-independentantigens(TI1).Theseincludeparacrystalline, identicalepitopesarrangedatapproximately 5 – 10 nmintervalsi ...

resultinerrors,oreventheactivationofoncogenes.Theresultsofthisprocess maythereforeincludethegenerationofB-celllymphomasandleukem ...

70 2 BasicPrinciplesofImmunology ProductionofMonoclonalAntibodies Fig.2. 10 Monoclonalantibodiesareproducedwiththehelpofcellline ...

repeatedinaregularpattern(lineare.g.,flagella,ortwo-dimensionale.g., viruses)withintervalsof 5 – 10 nm.Theseparacrystalline-patt ...

ofvarioustyrosinekinases(Fig.2. 11 )andmediatesstringentanddifferential regulationofseveralsignalingsteps.T-cellinductionandacti ...

ImmuneResponsesandEffectorMechanisms 73 T-CellActivation Fig.2. 11 RegulationofT-cellactivationiscontrolledbymultiplesignals,inc ...