Type IV hypersensitivity ... Type IV hypersensitivity is a cell-mediated immune reaction. In other words, it does not involve the participation of antibodies but ...ImmunesystemdisorderSections&MediaArticleIntroductionImmunedeficienciesHereditaryandcongenitaldeficienciesDeficienciescausedbyinfectionDeficienciescausedbydrugtherapyDeficienciescausedbymalnutritionDeficienciesassociatedwithlimitedenvironmentalexposureAllergiesTypeIhypersensitivitySensitization,activation,andeffectorphasesTypeIallergicreactionsTypicaltypeIallergensTreatmentoftypeIallergicresponsesTypeIIhypersensitivityTypeIIIhypersensitivityTypeIVhypersensitivityTuberculin-typehypersensitivityContacthypersensitivityanddermatitisAutoimmunedisordersBasicprocessesunderlyingautoimmunityAlterationofselfantigensReleaseofsequesteredselfantigensCross-reactionwithforeignantigensGeneticfactorsExamplesofautoimmunedisordersAutoimmunediseasesofthethyroidglandAutoimmunehemolyticanemiaPerniciousanemiaandautoimmunegastritisRheumatoidarthritisSystemiclupuserythematosusMultiplesclerosisTypeI(insulin-dependent)diabetesmellitusOtherautoimmunedisordersCancersofthelymphocytesGeneticcausesofcancerMalignanttransformationoflymphocytesTreatmentofcancersthroughidentificationofantigensMediaVideosImagesAdditionalInfoAdditionalReadingContributorsArticleHistoryLoadPreviousPageTypeIVhypersensitivityTypeIVhypersensitivityisacell-mediatedimmunereaction.Inotherwords,itdoesnotinvolvetheparticipationofantibodiesbutisdueprimarilytotheinteractionofTcellswithantigens.ReactionsofthiskinddependonthepresenceinthecirculationofasufficientnumberofTcellsabletorecognizetheantigen.ThespecificTcellsmustmigratetothesitewheretheantigenispresent.Sincethisprocesstakesmoretimethanreactionsinvolvingantibodies,typeIVreactionsfirstweredistinguishedbytheirdelayedonsetandarestillfrequentlyreferredtoasdelayedhypersensitivityreactions.TypeIVreactionsnotonlydevelopslowly—reactionsappearabout18to24hoursafterintroductionofantigentothesystem—but,dependingonwhetherthean