HelperTcellsarefoundintwodistinctcelltypes,Th1andTh2,distinguishedbythecytokinestheyproduceandrespondtoandtheimmuneresponsestheyareinvolvedin.Th1cellsproducepro-inflammatorycytokineslikeIFN-g,TNF-bandIL-2,whileTh2cellsproducethecytokinesIL-4,IL-5,IL-6andIL-13.ThecytokinesproducedbyTh1cellsstimulatethephagocytosisanddestructionofmicrobialpathogenswhileTh2cytokineslikeIL-4generallystimulatetheproductionofantibodiesdirectedtowardlargeextracellularparasites(see“IL-4SignalingPathway”).IL-5stimulateseosinophilresponses,alsopartoftheimmuneresponsetowardlargeextracellularparasites(see“IL-5SignalingPathway”)Th1andTh2areproducedbydifferentiationfromanon-antigenexposedprecursorcelltype,Thp.ExposureofThpcellstoantigenbyantigen-presentingcellsmayresultintheirdifferentiationtoTh0cells,notyetcommittedtobecomeeitherTh1orTh2cells,althoughtheexistenceofTh0cellsiscontroversial.CellscommittedaseitherTh1andTh2cellsarecalledpolarized,whethertheyareeffectorcellsactivelysecretingcytokinesorarememorycells.ThestimulationofThpcellsbyexposuretoantigen-presentingcellsinducestheproliferationofundifferentiatedcells,andtheirexpressionofIL-2andIL-2receptor.ThedifferentiationofTh1cellsandTh2cellsdependsonthecytokinestheyareexposedto.IL-12causesTh1differentiationandblocksTh2cellproduction(see“IL12andStat4DependentSignalingPathwayinTh1Development”pathway),whileIL-4causesTh2differentiationandantagonizesTh1development.IL-18alsoinducesTh1differentiation(See“IL-18signalingpathway”).PolarizedTh1andTh2cellsalsoexpressdistinctsetsofchemokinereceptorsthatfurthermodifytheirhomingandothercellularresponses(see“SelectiveexpressionofchemokinereceptorsduringT-cellpolarization”pathway).ImprovedunderstandingofTh1andTh2differentiationwillimproveouroverallunderstandingoftheimmunesystem,itsresponsetoinfectionandaberrantresponsesthatleadtodisease.

Contributor:

REFERENCES:

================  蚂蚁淘在线  ================

免责声明：本文仅代表作者个人观点，与本网无关。其创作性以及文中陈述文字和内容未经本站证实，对本文以及其中全部或者部分内容、文字的真实性、完整性、及时性本站不做任何保证或承诺，请读者仅作参考，并请自行核实相关内容

版权声明：未经蚂蚁淘在线授权不得转载、摘编或利用其他方式使用上述作品。已经经本网授权使用作品的，应该授权范围内使用，并注明“来源：蚂蚁淘在线”。违反上述声明者，本网将追究其相关法律责任。