Comparison of a new microscopic system for the measurement of residual leucocytes in apheresis platelets with flow cytometry and manual counting

Abstract

Since 2001, all blood components in Germany must be leucocyte depleted. Recently, a new method for quality control of depletion was introduced. Our study aimed at the validation of the method for routine use in apheresis platelet concentrates. We compared the new ADAM-rWBC device with manual counting in the Nageotte chamber and flow cytometry, two standard methods, by measuring residual leucocytes in 40 units of apheresis platelet concentrates and in six geometrical dilution series. Cell counts of residual leucocytes in the 40 units were below 10(6) cells per component with all methods, although mean cell counts were approximately 5 and 6 times higher in flow cytometry and ADAM-rWBC, respectively, compared to the Nageotte chamber. No unit with <10(6) leucocytes was regarded as contaminated. The dilution series showed acceptable accuracy, especially in the range around the cut-off (approximately 4·5cells/μl in components with a volume of 220ml) for regarding a concentrate as contaminated with leucocytes. No sample spiked with more than 4·5cells/μl was counted as having less. In comparison with manual counting and flow cytometry, the ADAM-rWBC device performed equally. The method is suitable for routine screening of leucocyte contamination of apheresis platelets.