| Abstract: | Leukocyte-poor red blood cells (RBCs) were prepared from one-to-seven-day-old whole blood using the IBM 2991 Blood Cell Processor. Blood was centrifuged at 3,000 rpm for 5 minutes on the initial processing cycle and for 1.5 minutes each subsequent cycle. The red blood cell override (RCO) control was used to remove portions of the leukocyte-rich red blood cell layer at the cell/liquid interface after separation. RBC loss was directly proportional to RCO time and averaged 5.4, 10.6, 15.6, 21.2, and 26.7 ml with RCO settings of 1.5, 2.5, 3.5, 4.5, and 5.5 seconds, respectively. A single RCO cycle removed 54.7, 66.0, 70.7, and 69.7 per cent of total leukocytes at RCO settings of 2.5, 3.5, 4.5, and 5.5 seconds, respectively. With double cycle processing at the same RCO times, 78.6, 88.9, 90.3, and 90.7 per cent of white blood cells were removed with loss of 12.4, 16.7, 22.4, and 25.4 per cent of RBCs respectively. Four-cycle processing with an initial 2.5-to-5.5-second RCO followed by three 1.5-second RCO cycles removed the greatest number of leukocytes (86.9, 93.3, 93.3, and 91.7 per cent, respectively) with corresponding RBC losses of 11.9, 17.2, 20.2, and 23.1 per cent. Total leukocytes contaminating the processed RBCs averaged 0.37, 0.18, 0.18, and 0.22 × 109, respectively. The processing cycle with the 3.5-second initial RCO provided maximal leukocyte removal and minimal erythrocyte loss. |
