Removal Of Plasma Components Research Articles

Lipopolysaccharide-induced hemolysis: Evidence for direct membrane interactions

While hemolysis in patients with sepsis is associated with increased mortality its mechanisms are unknown and Toll-like receptor (TLR)-4 mediated effects, complement-mediated hemolysis, or direct cell membrane effects are all conceivable mechanisms. In this study, we tested the hypotheses that toxic lipopolysaccharide (LPS) as well as non-toxic RS-LPS evokes hemolysis (1) by direct membrane effects, and (2) independent of the complement system and TLR-4 activation. We found, that incubation with LPS resulted in a marked time and concentration dependent increase of free hemoglobin concentration and LDH activity in whole blood and washed red cells. Red cell integrity was diminished as shown by decreased osmotic resistance, formation of schistocytes and rolls, and a decrease in red cell membrane stiffness. Non-toxic RS-LPS inhibited the LPS-evoked increase in TNF-α concentration demonstrating its TLR-4 antagonism, but augmented LPS-induced increase in supernatant hemoglobin concentration and membrane disturbances. Removal of plasma components in washed red cell assays failed to attenuate hemolysis. In summary, this study demonstrates direct physicochemical interactions of LPS with red cell membranes resulting in hemolysis under in vitro conditions. It might thus be hypothesized, that not all effects of LPS are mediated by TLR and may explain LPS toxicity in cells missing TLR.

Selective Plasma Component Removal: Alternatives to Plasma Exchange

Plasma exchange, the unselective removal of all plasma constituents, has been applied, with varying degrees of success, to an increasing number of disorders. Because of the high cost of plasma exchange, largely the result of expensive homologous replacement solution, and other reasons, alternatives have been sought. Selective removal of plasma components permits the use of autologous plasma as replacement which is less costly, more physiologic, and in some cases, a more efficient alternative to plasma exchange. The selective removal of plasma components whose presence is associated with a disease process can be accomplished presently by physical or chemical means with either on-line of off-line systems. A state-of-the-art review of currently available alternatives to plasma exchange is described. This includes hemoperfusion and plasmaperfusion over affinity columns or filters with immobilized sorbents. On-line separation of macromolecules by membrane filtration and cryoprecipitation as well as off-line chemical precipitation and cryoprecipitation are also described. The potential and limitations of the techniques are emphasized.