FactorsThatInfluenceImmunogenicityToprotectagainstinfectiousdisease,theimmunesystemmustbeabletorecognizebacteria,bacterialproducts,fungi,parasites,andvirusesasimmunogens.Infact,theimmunesystemactuallyrecognizesparticularmacromoleculesofaninfectiousagent,generallyeitherproteinsorpolysaccharides.Proteinsarethemostpotentimmunogens,withpolysaccha-ridesrankingsecond.Incontrast,lipidsandnucleicacidsofaninfectiousagentgenerallydonotserveasimmunogensunlesstheyarecomplexedwithproteinsorpolysaccharides.Immunologiststendtouseproteinsorpolysaccharidesasimmunogensinmostexperimentalstudiesofhumoralim-munity(Table3-1).Forcell-mediatedimmunity,onlypro-teinsandsomelipidsandglycolipidsserveasimmunogens.Thesemoleculesarenotrecognizeddirectly.Proteinsmustfirstbeprocessedintosmallpeptidesandthenpresentedto-getherwithMHCmoleculesonthemembraneofacellbe-foretheycanberecognizedasimmunogens.Recentworkshowsthatthoselipidsandglycolipidsthatcanelicitcell-mediatedimmunitymustalsobecombinedwithMHC-likemembranemoleculescalledCD1(seeChapter8).chapter3IImmunogenicityVersusAntigenicityIFactorsThatInfluenceImmunogenicityIEpitopesIHaptensandtheStudyofAntigenicityIPattern-RecognitionReceptorsAntigensSimmunoglobulinreceptorofBcells,orbytheT-cellreceptorwhencomplexedwithMHC,arecalledantigens.Themolecularpropertiesofantigensandthewayinwhichthesepropertiesultimatelycontributetoimmuneactivationarecentraltoourunderstandingoftheimmunesystem.Thischapterdescribessomeofthemolecu-larfeaturesofantigensrecognizedbyBorTcells.Thechap-teralsoexploresthecontributionmadetoimmunogenicitybythebiologicalsystemofthehost;ultimatelythebiologicalsystemdetermineswhetheramoleculethatcombineswithaBorTcell’santigen-bindingreceptorcantheninduceanim-muneresponse.FundamentaldifferencesinthewayBandTlymphocytesrecognizeantigendeterminewhichmolecularfeaturesofanantigenarerecognizedbyeachbranchoftheimmunesystem.Thesedifferencesarealsoexaminedinthischapter.Immunogenicity...
