A novel true volumetric method for the determination of residual leucocytes in blood components

Background and Objectives Accurate determination of residual leucocytes [white blood cells (WBC)] in blood components is of high clinical importance. To date, several labour-intensive, time-consuming or expensive techniques have been used for this purpose. Materials and Methods A method for the determination of residual WBC is described using a novel low-cost flow-cytometric cell counter and analyser (CCA). The DNA in WBC was stained using 4'-6-diamidino-2-phenylindole (DAPI) and WBC were automatically analysed by true volumetric counting of 200-mul samples (prepared from a 20-mul undiluted sample). Results Dilution experiments over a range of 0.5-50 WBC/mul showed a linearity of r = 0.998. The detection limit of this method was 0.83 WBC/mul of red blood cell concentrate (RCC) and 0.67 WBC/mul of platelet concentrate (PC), with an accuracy of 95.5%. Conclusion Residual WBC (< 1 WBC/mu l) can be accurately counted using the CCA within 2 min and at a total cost of less than cent 1 per sample.