A flow cytometric technique to accurately measure post-filtration white blood cell counts.
Leukocyte-depleted blood products are being used with increasing frequency in hopes of preventing or delaying platelet alloimmunization. However, accurately monitoring the efficiency of leukocyte (WBC) removal is a difficult problem because electronic cell counters are not accurate at very low WBC numbers and hemocytometer counts are tedious and time consuming. A simple flow cytometric technique was developed which accurately and rapidly measures extremely low WBC counts. Using a propidium iodide solution which causes DNA to fluoresce, the residual WBC count was measured in 42 units of blood products after leukocyte depletion using a commercial filter. There was a significant correlation with simultaneous hemocytometer counts, r = 0.672, but residual WBC could be identified in every unit using the flow cytometer, whereas in 19% of the units no WBC were seen using the hemocytometer. Extremely low counts, as low as a single WBC/4 microliters could be reproducibly obtained. In addition, serial dilution studies yielded a correlation coefficient of 0.997. Because most clinical laboratories now have access to flow cytometers, this technique can be widely used.
University of Kansas Medical Center, Kansas City.
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Bodensteiner
D001781:Blood Component Removal / Q000295:instrumentation / Q000379:methods; D004247:DNA / Q000032:analysis; D017707:Erythrocyte Transfusion; D005374:Filtration; D005434:Flow Cytometry / Q000379:methods; D006801:Humans; D007958:Leukocyte Count / Q000379:methods; D017708:Leukocyte Transfusion; D007962:Leukocytes / Q000032:analysis; D017713:Platelet Transfusion
D004247:DNA