The effect of different Escherichia coli endotoxins on red blood cell deformability

Lipopolysaccharide (LPS) of grant-negative bacteria consists of O-specific polysaccharide chain, core oligosaccharide chain and lipid A. Studies on the effect of various endotoxins on red blood cell (RBC) deformability gave conflicting results. To evaluate whether the effect of endotoxin on RBC deformability depends on the presence and exposure of lipid A, we studied the effect of five E.coli LPS components on RBC deformation by means of a shear stress diffractometer: 1) complete E.coli 0111:B4 LPS; 2) delipidated E.coli 0111 B4 LPS; 3) R-mutant E.coli F-583 LPS lacking the O-specific polysaccharide chain; 4) E.coli F-583 lipid A, and 5) electrodialysed E.coli F-515 lipid A. Electrodialysis results in highly dispersed molecules whereas unelectrodialysed LPS tends to form aggregates. At a shear stress of 6 Pa RBC deformation was not changed by complete and delipidated LPS, but RBC deformation was impaired by Rd-mutant LPS (−12 %) and lipid A F-583 (−10 %) after 30 min incubation. Electrodialysed lipid A F-515 showed the strongest effect and decreased RBC deformation (−24 %) after 30 min incubation. These results indicate that the effect of LPS on RBC deformation depends on the exposure of lipid A for binding to RBC membranes. The polysaccharide chain of LPS weakens the interaction of lipid A and RBC membranes. Furthermore, aggregates of lipid A impair RBC deformation less than highly dispersed lipid A.