Visualization of the molecular dynamics of lipopolysaccharide on the plasma membrane of murine macrophages by total internal reflection fluorescence microscopy.

The molecular action of Alexa 594-labeled lipopolysaccharide (LPS) from Escherichia coli was examined on living peritoneal macrophages of C57BL/6 mice by total internal reflection fluorescence microscope (TIRFM), and the molecular kinetics of LPS was analyzed. TIRFM visualization of the action of fluorescence-labeled LPS revealed an increase in the mean fluorescence intensity of LPS on the plasma membrane of wild type macrophages at 60 min after administration, indicating the oligomerization of LPS after binding to the macrophages. Additionally, a time-dependent sharp decrease in the mean diffusion coefficient of LPS was observed.