ABSTRACT
<p><b>OBJECTIVE</b>To investigate the binding characteristics of endothelial cell (EC) with LPS free from the participation of serum factors.</p><p><b>METHODS</b>Laser confocal microscope was employed in the observation of the binding of EC with FITC-LPS. The KD and the binding sites of each EC were calculated by radioligand binding assay of receptors (RBA) using [(3)H]-LPS.</p><p><b>RESULTS</b>The binding of EC with LPS was saturable, time and concentration dependent and it could be competed with overdosed LPS of the same type. The fluorescence mainly distributed in cytoplasm, especially near the nucleus, which could also be stained.</p><p><b>CONCLUSIONS</b>There might be some specific LPS binding sites existing on ECs and LPS could function intracellularily.</p>