No abstract

Methodology is presented for enumerating very low concentrations of white cells (WBCs) in red cells (RBCs) by two separate measurement techniques. Both techniques rely on the method of harvesting WBCs from a 300- to 350-mL unit of RBCs and concentrating them to a volume of approximately 0.5 to 1.0 mL, which is equivalent to a WBC concentration of approximately 550 to 1. The WBC separation and concentration steps require less than 3 hours to complete, and multiple RBC units can be processed in parallel. Cell counting is carried out in a fluorescence hemocytometer or by a modified cytospin technique. As few as 1000 WBCs in a unit of RBCs, which corresponds to a more than 6 log10 WBC depletion, can be measured without reaching the sensitivity limit of either technique (800 and 200 WBC/unit, respectively). The harvesting method and counting techniques are relatively simple and inexpensive.

White cell (WBC) reduction of blood components has been receiving increased attention as a way of reducing transfusion-related complications such as WBC-associated HLA alloimmunization and transmission of cell-associated viral diseases. Currently available filters are limited to removing approximately 3 log10 (99.9%) of WBCs from red cells (RBCs). The performance of two experimental filters that were designed to remove 6 log10 WBCs from fresh RBCs during component preparation was evaluated. Both filters were able to meet this objective in less than 40 minutes with RBC losses of less than 15 percent under nonoptimized conditions. Filtered RBCs showed storage parameters within the normal range over a 42-day period. The use of these filters, if combined with a sterile docking device or if incorporated into a collection set, should provide the means to supply highly WBC-reduced RBCs with a normal shelf life.