Particle-size analysis of leukocytes with cytometers based on the impedance method makes it possible to distinguish three types of white cells in blood (small cells, medium-sized cells and large cells). In order to test the ability of such a three-part dif cytometer to screen for abnormal cells of the leukocyte series, we assayed the differentiation of white cells in 786 blood samples with the Sysmex E-4000 and compared the results with those of the Technicon H6000, a cytochemical cytometer.

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... small cell and large cell fractions of the Sysmex E-4000 correlated very well with the percentages of lymphocytes and neutrophils measured with the Technicon instrument and showed good sensitivity and specificity in discriminating samples with normal and abnormal results. The percentage of the medium-sized cells correlated significantly with the contents of eosinophilic, monocytic and basophilic cells as assayed with the Technicon R6000; but for a satisfactory determination of each of these cell lines (sensitivity of more than 90% and ca. 70% specificity) it was necessary for them to represent more than 10% of the medium-sized cell population.