Transfusions with young erythrocytes (neocytes) in sickle cell anemia.

Transfusion-induced hemochromatosis is a potential therapeutic complication of the management of sickle cell anemia. Selective transfusion with young erythrocytes (neocytes), which theoretically have a longer life-span than do regular donor red cells, could decrease transfusion frequency and reduce iron deposition in the sickle cell patient. Using blood cell separators, a method has been devised to prepare neocyte units for transfusion. Neocyte enrichment was evaluated by reticulocyte count and mean red cell age was estimated from erythrocyte pyruvate kinase, an age-dependent enzyme. These neocyte units have an average estimated men cell age of 30 days compared to 60 days for unfractionated units. Radiochromium studies in seven splenectomized thalassemia major patients revealed an average half-life of 47.4 days for neocytes stored in the frozen state compared to an average half-life of 29.5 days for standard frozen red cells. Neocyte aliquots collected from three normal, eusplenic donors had an average estimated mean cell age of 6.5 days and an average half-life of 57.2 days when reinfused. Neocyte units cost +300 to collect and process compared to $92 for frozen red cells, but use of neocyte units could reduce by one-half the transfusion requirement in transfusion-dependent patients.