Optimal leukocyte removal from refrigerated blood with the IBM 2991 blood cell processor.

One hundred forty-six units of two to five-day-old refrigerated blood were washed with the IBM Blood Cell Processor. The ABO and Rh types of the units varied according to available inventory. This study was designed to select the best protocol from the 42 possible combinations utilizing the machine's variable red blood cell override (RCO). A one liter wash program was used. The two parameters selected for study were the per cent red blood cell recovery and the per cent white blood cell removal. The protocol of choice uses a RCO of four seconds in the first and second steps of the program. This protocol yields a washed unit with a mean red blood cell recovery of 82 per cent and a mean white cell removal of 93 per cent. Our studies indicate that the IBM Blood Cell Processor can be used to wash two to five day old refrigerated blood for the preparation of leukocyte-poor blood that would meet the Standards of the AABB.