Objective:Toinvestigatethebindingcharacteristicsofendothelialcell(EC)withLPSfreefromtheparticipationofserumfactors.Methods:LaserconfocalmicroscopewasemployedintheobservationofthebindingofECwithFITC-LPS.TheKDandthebindingsitesofeachECwerecalculatedbyradioligandbindingassayofreceptors(RBA)using[3H]-LPS.Results:ThebindingofECwithLPSwassaturable,timeandconcentrationdependentanditcouldbecompetedwithoverdosedLPSofthesametype.Thefluorescencemainlydistributedincytoplasm,especiallynearthenucleus,whichcouldalsobestained.Conclusions:TheremightbesomespecificLPSbindingsitesexistingonEcsandLPScouldfunctionintracellularily.