ADHESION-RELATED GLYCOCALYX STUDY - QUANTITATIVE APPROACH WITH IMAGING-SPECTRUM IN THE ENERGY-FILTERING TRANSMISSION ELECTRON-MICROSCOPE (EFTEM)

Large polysaccharide molecules composing the glycocalyx have been show n to prevent cell adhesion. However, this process was not observed mic roscopically. Terbium labeling, combined with a new quantitative imagi ng method based on electron energy loss spectroscopy, allowed specific glycocalyx staining with excellent contrast. Image analysis enabled u s to compare glycocalyx structure in free membrane areas and contacts between monocytic cells and bound erythrocytes. Apparent glycocalyx th ickness, in contact areas, was half of the sum of glycocalyx thickness es in free areas without label density increase. Ultrastructural immun ogold localization of CD43 molecules, a major component of glycocalyx, was also demonstrated to be excluded from contact areas during adhesi on. Thus, both approaches strongly suggest that some glycocalyx elemen ts must exit from contact to allow binding of adhesion molecules. (C) 1998 Federation of European Biochemical Societies.