最新抗原是能够刺激机体免疫系统产生特异性免疫应答30-药学医学精品资料.ppt

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1、最新抗原是能够刺激机体免疫系统产生特异性免疫应答30-药学医学精品资料1ConceptofAntigenAntigensaresubstancesthatinduceaspecificimmuneresponseandsubsequentlyreactwiththeproductsofaspecificimmuneresponse.抗原是能够刺激机体免疫系统产生特异性免疫应答、并能与相应免疫应答产物（抗体或致敏淋巴细胞）在体内外发生特异性结合的物质，也叫免疫原(immunogen)。Anantigenisamoleculethatstimulatesanimmunere

2、sponse.Thewordoriginatedfromthenotionthattheycanstimulateantibodygeneration.Wenowknowthattheimmunesystemdoesnotonlyconsistofantibodies.Themoderndefinitionencompassesallsubstancesthatcanberecognizedbytheadaptiveimmunesystem.EndogenousantigensEndogenousantigensareantigensthathavebeengenera

3、tedwithinthecell,asaresultofnormalcellmetabolism,orbecauseofviralorintracellularbacterialinfection.AutoantigensAnautoantigenisusuallyanormalproteinorcomplexofproteins(andsometimesDNAorRNA)thatisrecognizedbytheimmunesystemofpatientssufferingfromaspecificautoimmunedisease.Theseantigensshou

4、ldundernormalconditionsnotbethetargetoftheimmunesystem,butduetomainlygeneticandenvironmentalfactorsthenormalimmunologicaltoleranceforsuchanantigenhasbeenlostinthesepatients.TumorantigensTumorantigensarethoseantigensthatarepresentedbytheMHCImoleculesonthesurfaceoftumorcells.Theseantigensc

5、ansometimesbepresentedonlybytumorcellsandneverbythenormalones.Inthiscase,theyarecalledtumor-specificantigens(TSAs)andtypicallyresultfromatumorspecificmutation.2CharacteristicsofAntigen★Immunogenicity免疫原性Thecapacitytostimulatetheproductionofantibodiesorcell-mediatedimmuneresponses.★Antige

6、nicity抗原性（反应原性）Theabilitytobindantibody.♣Completeantigen完全抗原♣Incompleteantigen,alsoknownashapten不完全抗原，或半抗原Incompleteantigenshaveantigenicdeterminants,butcannotinduceimmuneresponsesbecausetheylackoneormoreoftheimportantattributesneededforthisfunction(oneexampleofanincompleteantigenisahapt

7、en,whichisanartificialmonovalentepitope)3PropertiesofantigenForeignnessisessentialtoimmunogenicitybecauseself-responsivecellsareeliminatedduringlymphocyteontogeny,leavingonlycellsthatrespondtonon-self,so-called"foreign"epitopes.异物性Specificity特异性HighmolecularweightMolecule