The Removal of in Vitro Damaged Erythrocytes from the Circulation of Normal and Splenectomized Rats

The in vitro alterations and in vivo fate of erythrocytes treated with N-ethylmaleimide or subjected to prolonged incubation were studied in normal and splenectomized rats. Minimal injury (20 µM NEM/ml. RBC) resulted in red cells with decreased osmotic fragility and increased plasticity; however, mechanical fragility was significantly increased. These cells were removed with a half-time of 78 minutes, mainly by splenic sequestration, and splenectomy prolonged their life span. Incubation at 37 C. for 21 hours produced erythrocytes with increased osmotic and mechanical fragility and decreased plasticity. Erythrocyte clearance was more rapid (T½ = 59 minutes), with spleen and liver removing approximately an equal number of cells and splenectomy having little effect on red cell life span. With severe injury (40 µM NEM/ml. RBC), all three in vitro measurements showed marked alterations, red cell removal was rapid (T½ = 35 minutes), mainly by hepatic sequestration, and clearance was unaffected by splenectomy.

The present studies have shown that chemical injury or prolonged incubation lead to profound changes in in vitro tests of red cell integrity, the mechanical fragility predicting most closely the subsequent in vivo events. Although the entire reticuloendothelial system appears to participate in red cell removal, the spleen and liver are the major sites of sequestration in the rat. The splenic removal predominates with minimally injured cells, hepatic removal with moderately and severely altered cells. The type of injury appears to be of less significance than the degree of injury of the red cells.