Themainapproachtoreducegraftrejectionhasbeenfocusedonthedevelopmentofimmunosuppressiveagentsatpresent.Althoughthesestrategieshavereportedlyreducedgraftrejection,therehasbeenareciprocalincreaseinmoresevereimmunosuppressionandlethalinfections,aswellasseveresideeffects.BlockadeofcostimulatoryTcellresponsehasbeenprovedasoneofusefulstrategiestoreducegraftrejection.Furthermore,ithasbeenshownthatinfusionofdendriticcells(DCs)withapotentnegativeregulatoryabilityforTcellscouldprolongallograftsurvival.InthisstudymouseDCs(mDCs)weretransfectedwiththerecombinantplasmidpcDNA3.0containingmouseinduciblecostimulator-Ig(mICOS-Ig)cDNAbyelectroporation.ThetransientexpressionofmICOS-IginmDCcouldbedetectedbyELISAandSDS-PAGE.MouseICOS-IgfusionproteinexpressedinmDCandmICOS-Iggene-modifiedmDCcouldinhibitlymphocyteproliferationinmixedlymphocyteculture(MLC)invitro.Furthermore,mICOS-Iggene-modifiedmDCcouldinhibitlymphocyteproliferationinrecipientmice.TheseresultssuggestedthatmICOS-Iggene-modifiedmDCexertedinhibitoryeffectsonTcells,andmightbesuitablefortreatmentorpreventionofgraftrejectionandimmunopathologicdiseases.