Behaviour of young and old desialylated rabbit erythrocytes in vivo

Young and old rabbit erythrocytes, separated by density gradient centrifugation, were desialylated by neuraminidase treatment and reinjected into the animal after 51Cr labelling. Both red cell populations are quickly removed from the circulation and trapped by the liver; then a large percentage of the young cells reappear in the peripheral blood and behaves like untreated erythrocytes; old cells, on the contrary, do not return to the blood stream and are probably lysed in the liver. These results suggest that a sialic acid repair can occur on the membrane of young erythrocytes and confirm that the loss of this molecule is not by itself sufficient to determine the death of the cell.