COMPARATIVE-EVALUATION OF 3 FLOW CYTOMETERS FOR RETICULOCYTE ENUMERATION

Flow cytometric determination of reticulocytosis is progressively repl acing the manual microscopic method. We evaluated three flow cytometer s (Becton Dickinson FACScan, Coulter EPICS Profile II, Ortho Cytoron A bsolute) for reticulocyte enumeration, using thiazole orange. For each sample, 30 000 cells were analysed. In order to comparatively evaluat e the three instruments, reticulocytes were counted by manually gating the erythroid population and evaluating the gated population for fluo rescence characteristics. The different instruments showed good linear ity and precision. No carry-over was observed. Orthogonal regression a nalysis of reticulocyte counts of 100 healthy blood donor samples and 108 haematological patient samples showed a good mutual comparability between all three instruments tested, although the paired t-test showe d a significant difference between the Cytoron and both the FACScan an d the Profile. Despite minor statistical differences, the three instru ments can be considered equivalent for daily routine reticulocyte enum eration.