The usefulness of the “Imm Gran?” flag reported on by the Sysmex XE-5000.

Heidi Eilertsen1, Tor-Arne Hagve2,*

1Faculty of Health Sciences, Oslo and Akershus University college of Applied Sciences, Oslo, 2Multidiciplinary Laboratory Medicine and Medical Biochemistry, Akershus University Hospital, Lørenskog, Norway

Introduction: Sysmex XE-5000 counts immature granulocytes (IGs) in the differential (DIFF) channel based on flow cytometry. Information on immature cells is also derived from the IMI channel based on radiofrequency and direct current measuring principles. In the IMI channel, not only IGs but also bands and myeloblasts are detected. If a difference occurs between the numbers of cells detected in the two channels, an “Imm Gran?” flag is reported.

Objectives: The aim of this study was to evaluate the analytical and diagnostic performance of immature granulocyte measurements as well as the usefulness of the IG flag reports questioning the need of a slide review or a manual count of samples with a flag report. The inter instrument agreement and the accuracy of the immature granulocyte counts, as well as the usability of the immature granulocyte flag reports, were studied by comparing with a manual differential.

Methods: 408 samples were analysed on 3 XE-5000 instruments. The IG count and the “Imm Gran?” flag reports from all 3 instruments were used for reproducibility studies. The diagnostic performance of the automated IGs and the “Imm Gran?” flag were studied by comparing the XE-5000 results with the results of the manual differential.

Results: The reproducibility of the “Imm Gran?” flagging between instruments was poor (қ value 0.75-0.80). The most significant contributor to the report of the “Imm Gran?” flag was shown to be bands and the flag played a minor role in detecting blasts. The inter-instrument reproducibility of the IG counts was high (ICC value 0.99). The IG count reported by XE-5000s was higher than the manual IG count (36-55%) and the difference as well as the variability tend to increase with increasing levels of IGs.

Conclusion: The “Imm Gran?” flag has a poor analytical quality and give no substantial information on the presence of blasts in the sample. We therefore suggest reporting the automated IG count without initial microscopic slide review.

Keywords: Biomarker, Method