(1) Three sickle cell patients were sustained at normal hemoglobin levels for 3-4 months by means of repeated transfusions of fresh blood.
(2) In response to transfusions, there was a decline in reticulocytes to normal levels during the first 5-7 days of observation. During periods in which the hemoglobin was maintained at high-normal or super-normal levels, the reticulocyte values were depressed below the normal range. A distinct reticulocyte response was observed when the hemoglobin declined to approximately 11.0 Gm. per cent following cessation of transfusions.
(3) Employing anti-M differential agglutination, a simple exponential decline was observed in the number of sickle cells in each patient’s circulation during the period of sustained normal hemoglobin concentration.
(4) The continued production of new sickle cells during the first week of observation complicated the interpretation of the differential agglutination data, but provided indirect evidence for the presence of an especially short-lived proportion of the patient’s cells. Support for this concept was derived from the radioactive iron utilization studies performed in Case 1.