Erythrocyte-endothelium adhesion can be induced by dextran.

Plasma proteins have been identified to play a key role in the increased adhesiveness of red blood cells (RBC) to endothelial cells (EC) in various diseases associated with vascular complications. However, the underlying mechanisms on how plasma proteins facilitate adhesion remain unclear. In this study, we investigated if macromolecular depletion is able to induce adhesion of RBC to EC. RBC were suspended in solutions containing the neutral polyglucose dextran to mimic the effects of nonadsorbing macromolecules and the dynamics of RBC-EC adhesion were recorded using a parallel plate flow chamber system. Cell adhesion was markedly increased in the presence of dextran with a molecular mass larger than 70 kDa, with this increase reflected by both the number of cells adhering and the strength of the adhesion. This increased adhesiveness is attributed to reduced surface concentrations of the large polymers and hence attractive forces due to depletion interaction. Our results thus provide a rational explanation on how nonadsorbing plasma proteins could play a significant role in abnormal RBC-EC adhesion in vivo.