A method for the increased extraction of cholesterol from human red blood cells by modified plasma lipoprotein

The in vitro extraction of cholesterol from erythrocytes by plasma lipoproteins of reduced cholesterol content would be expected to be free of cholesterol-unrelated alterations of the cell membrane. The earlier application of this method utilized whole blood plasma in which the major part of the lipoprotein cholesterol was esterified by the plasma enzyme lecithin-cholesterol acyl transferase (LCAT) in a preliminary incubation. Because of the cholesterol remaining unesterified in the plasma, only 35% of the cell cholesterol could be removed. The method reported here uses HDL3, a plasma lipoprotein which is the preferred substrate for LCAT, instead of whole plasma for the extraction. Multiple extractions with LCAT treated HDL3 resulted in the removal of up to 77% of the erythrocyte cholesterol with only minor hemolysis.