Quantitative study of erythrocyte-lysolecithin interaction

Red cell metabolic and membrane features in haemolytic anaemia of alcoholic liver disease (Zieve's syndrome)

Zieve's syndrome (ZS), which consists of transient haemolytic anaemia, jaundice, hyperlipoproteinaemia, and alcohol-induced liver disease, was studied in male patients during the acute (n = 20) and the remittent (n = 10) phase. Chronic alcoholics (n = 10) without haemolysis and healthy male persons (n = 10) served as controls. Erythrocytes were separated into old and young cells by means of density-layer centrifugation. Those fractions which contained older red cells disclosed a pyruvate-kinase instability which resulted in impaired metabolism. Changes in membrane lipid composition as indicated by increased cholesterol and polyunsaturated fatty acids (PUFA) were also detected in patients during the acute phase of ZS. Alcohol-induced red-cell vitamin-E deficiency with a decrease in PUFA levels may provoke an oxidation of reduced red-cell glutathione which in turn results in the enzyme instability. This study lends further support to the hypothesis that the putative role of the red-cell metabolic injury in the origin of haemolysis in ZS cannot be envisaged without introducing membrane-linked and extracellular cofactors.

The significance of plasma lipoproteins on erythrocyte aggregation and sedimentation

Increased erythrocyte aggregation can be induced by high concentrations of human lipoproteins. The dependence of aggregate formation on lipoprotein concentration was recorded by determination of erythrocyte sedimentation rate (ESR), by electrical measurement of the erythrocyte aggregation index (EAI) and by scanning electron microscopy. The lipoprotein concentrations necessary to induce a significantly increased ESR in an otherwise normal human plasma are much too high to be encountered in physiologic or even severe pathologic states. Therefore hyperlipoproteinaemia by itself cannot explain a raised ESR. In cases where the ESR is raised due to the presence of increased amounts of other erythrocyte aggregating plasma proteins (agglomerins), hyperlipoproteinaemia can contribute to a limited extent to the increase in ESR. The possible pathophysiological significance of the demonstrated erythrocyte aggregating capacity of human lipoproteins in a microvascular environment is noted.

Topological asymmetry of phospholipid metabolism in rat erythrocyte membranes. Evidence for flip-flop of lecithin

1. The distribution of phospholipids between inside and outside of rat erythrocyte membranes was studied by incubating the cells with phospholipase A2 from Naja naja venom and sphingomyelinase from Staphylococcus aureus. 2. Choline-containing phospholipids were found to comprise the majority of the outer layer of the membrane. 3. The incorporation of radioactive fatty acids into phospholipids occurred predominantly at the inside of the membrane. 4. Exchange of phospholipids between red cell membranes and plasma lipoproteins occurred at the outside of the membrane. 5. Indications were found for a rather slow flip-flop of lecithin across the membrane.