The flow cytometry myeloid progenitor count: A reproducible parameter for diagnosis and prognosis of myelodysplastic syndromes

Abstract

Background: The bone marrow blast count is central to the diagnosis and monitoring of myelodysplastic syndromes (MDS). It is an independent risk factor for worse prognosis whether based on the morphology blast count or the flow cytometry (FC) myeloid progenitor (MyP) count. It is a principal population in FC MDS analysis also because once defined; it provides significant contributions to the overall FC MDS score. Methods:We elected to investigate inter-analyst agreement for the most fundamental parameter of the FC MDS diagnostic score: the MyP count. A common gating strategy was agreed and used by seven cytometrists for blind analysis of 34 routine bone marrows sent for MDS work-up. Additionally, we compared the results with a computational approach.Results: Concordance was excellent: Intraclass correlation was 0.993 whether measuring %MyP of total cells or CD45+ cells, and no significant difference was observed between files from different centers or for samples with abnormal MyP phenotypes. Computational and manual results were similar. Applying the common strategy to individual laboratories' control cohorts produced similar MyP reference ranges across centers. Conclusion:The FC MyP count offers a reliable diagnostic and prognostic measurement in MDS. The use of manual and computational approaches side by side may allow for optimizing both strategies. Considering its known prognostic power, the MyP count could be considered a useful and reliable addition to existing prognostic scoring systems.

Optimization of monocyte gating to quantify monocyte subsets for the diagnosis of chronic myelomonocytic leukemia

“…Indeed, results of a survey by this group, which has led the path in implementing this test, show that a substantial number of institutions were using a suboptimal tube and acquiring an insufficient number of events (Tarfi et al, 2018), perhaps signaling that insufficient emphasis had been placed on specific details of the test, including the importance of the gating strategy. Our results indicating variable results when using different gating strategies—and thus highlighting the importance of the gating strategy when quantifying flow cytometric parameters—is in line with a recent illuminating study showing that different gating strategies led to substantially different results when quantifying CD34+ myeloid progenitors in the bone marrow (Johansson et al, 2021).…”

“…In CMML but not in other causes of monocytosis, intermediate and nonclassical monocytes are practically absent [Color figure can be viewed at wileyonlinelibrary.com] placed on specific details of the test, including the importance of the gating strategy. Our results indicating variable results when using different gating strategies-and thus highlighting the importance of the gating strategy when quantifying flow cytometric parameters-is in line with a recent illuminating study showing that different gating strategies led to substantially different results when quantifying CD34+ myeloid progenitors in the bone marrow(Johansson et al, 2021).…”

Multiparameter flow cytometry in the evaluation of myelodysplasia: Analytical issues

“…It has also identified an increased SSC of more mature erythroid cells as a highly informative feature of MDS-associated dysplasia (Duetz et al, 2021;Westers et al, 2023). This finding was independently confirmed by others using traditional analysis (Johansson et al, 2021). Likewise, Barreau et al (2020) developed a semi-automated approach for a MFC diagnosis of MDS.…”

Myelodysplastic neoplasms dissected into indolent, leukaemic and unfavourable subtypes by computational clustering of haematopoietic stem and progenitor cells

“…The value of the LSC frequency in AML is widely accepted for predicting survival and relapse at diagnosis and post-treatment, respectively [ 28 , 29 ]. In MDS, the myeloid progenitor count is used as a prognostic parameter in FCM scores, whereas we recently showed that manually gated LSCs predict leukaemic progression [ 20 , 23 , 30 ]. Yet, manual gating of the low-frequent LSCs is sensitive to errors.…”