Haemolysis in patients with chronic lymphocytic leukaemia during extracorporeal irradiation of the blood

The effect in vitro of ionizing irradiation and small rises in temperature on the uptake and release of labelled lipids by the human erythrocyte membrane

1. The effect of X-irradiation (50 000 rad) and an increase in temperature from 37 to 42 degrees C on the synthesis, uptake and release of labelled lipids by erythrocytes was studied in plasma incubations in vitro. 2. Both irradiation and a rise in temperature resulted in an inhanced synthesis of [32P]phosphatidic acid in the erythrocytes. 3. The uptake by the erythrocytes of 14C- and 3H-labelled cholesterol, [14C, 32P]phosphatidylethanolamine and [14C, 32P]phosphatidylcholine from plasma lipoproteins was increased by a rise in temperature but not by irradiation. These labelled lipids were apparently taken up in the ratio in which they were found in plasma. They were not released from the erythrocytes in the same manner.

Hemolytic anemias. Failure of the red cell membrane

The normal erythrocyte membrane is composed of nearly equivalent amounts of lipid and protein. The lipid portion of the membrane has been well studied. Even though de novo synthesis of lipid does not occur in human red cells, many biochemical pathways exist which facilitate detoxification of lipid breakdown products and lipid renewal. Rare defects in these processes are associated with hemolytic disorders. Recent studies have revealed that the membrane proteins are diverse and suggest that protein dysfunction may also account for clinical disease. Protein and lipid are entwined in a physicochemical relationship which is probably best depicted by the classic lipid bilayer with interspersed proteins in both the inner and outer surfaces and also spanning the bilayer. Membrane failure results in hemolytic anemia. This failure can be intrinsic, caused by abnormal lipid or protein constituents; or extrinsic, with a normal membrane being unable to counteract physical, chemical or immunologic stress. Clinical examples of membrane failure and hemolytic anemia can be separated into three groups according to the predominant mechanism of the hemolysis: fragmentation, whole-cell lysis, and filtration and entrapment. Although these mechanisms can act separately or in concert, the final hemolytic destruction of the cell can usually be traced to a failure of membrane function.