Standardization of flow cytometry in myelodysplastic syndromes: report from the first European LeukemiaNet working conference on flow cytometry in myelodysplastic syndromes

Abstract

The myelodysplastic syndromes are a group of clonal hematopoietic stem cell diseases characterized by cytopenia(s), dysplasia in one or more cell lineages and increased risk of evolution to acute myeloid leukemia (AML). Recent advances in immunophenotyping of hematopoietic progenitor and maturing cells in dysplastic bone marrow point to a useful role for multiparameter flow cytometry (FCM) in the diagnosis and prognostication of myelodysplastic syndromes. In March 2008, representatives from 18 European institutes participated in a European LeukemiaNet (ELN) workshop held in Amsterdam as a first step towards standardization of FCM in myelodysplastic syndromes. Consensus was reached regarding standard methods for cell sampling, handling and processing. The group also defined minimal combinations of antibodies to analyze aberrant immunophenotypes and thus dysplasia. Examples are altered numbers of CD34 + precursors, aberrant expression of markers on myeloblasts, maturing myeloid cells, monocytes or erythroid precursors and the expression of lineage infidelity markers. When applied in practice, aberrant FCM patterns correlate well with morphology, the subclassification of myelodysplastic syndromes, and prognostic scoring systems. However, the group also concluded that despite strong evidence for an impact of FCM in myelodysplastic syndromes, further (prospective) validation of markers and immunophenotypic patterns are required against control patient groups as well as further standardization in multi-center studies. Standardization of FCM in myelodysplastic syndromes may thus contribute to improved diagnosis and prognostication of myelodysplastic syndromes in the future. Cancer and Immunology, Cancer Center Amsterdam, De Boelelaan 1117, 1081 HV, Amsterdam, The Netherlands. E-mail: a.vandeloosdrecht@vumc.nl © F e r r a t a S t o r t i F o u n d a t i o n

Clinical utility of multiparameter flow cytometry in the diagnosis of 1013 patients with suspected myelodysplastic syndrome

“…MFC is capable of identifying dysplastic features in BM samples and, thus, was supposed to be added to the diagnostic workup in patients who have suspected MDS. [13][14][15][16]32,34 In the current study, several aspects regarding the specificity and sensitivity of MFC for diagnosing MDS have been elucidated in agreement with previous studies. 15,16 In the current series and in the data reported by van de Loosdrecht et al, 16 this also is true for the identification of dysplastic features in cell lineages that were not rated dysplastic by CM alone.…”

“…Further studies should be performed to confirm these results and especially to define standards for the application of MFC in the diagnostic workup of MDS. 34,35 …”

Standardization of flow cytometry in myelodysplastic syndromes: a report from an international consortium and the European LeukemiaNet Working Group

“…2 This approach requires consensus regarding sample processing, antibody combinations and data analysis. The optimal methods for processing and handling samples for FC in MDS were previously published by the ELN Working Group in 2009 6 and are summarized in Table 2. Table 3 presents the core markers that should enable to evidence the abnormal expression of specified antigens and the relation between antigens of relevance in specific cell populations.…”

“…Antibody combinations, such as CD45/CD34/CD117/HLA-DR and CD45/CD34/CD123/ HLA-DR (Figure 1), are recommended to distinguish myeloid progenitor cells from other populations, such as B-cell precursors, monoblasts, basophils, erythroblasts and plasmacytoid dendritic cell precursors, which might show overlapping CD45 and SSC features. 6 Thus, multiple strategies must be applied to identify and enumerate the myeloid progenitor cells present in MDS: (a) CD45 dim SSC low/int ; (b) CD45 dim SSC low/int CD34 þ (negative for lymphoid markers such as CD19); (c) CD45 dim SSC low/int HLA-DR þ CD11b À (B-cell precursors excluded by SSC low and/or CD19 expression); and (d) CD45 dim SSC low/int HLA-DR þ CD117 þ . 13 The percentages of myeloid progenitor cells obtained with these definitions should correlate, unless the aberrant myeloid progenitor cells lack a particular antigen (e.g., loss of HLA-DR, CD34, or occasionally CD45) or aberrantly gained expression of, for example, CD19.…”

“…3 --5 The first international workshop from the European LeukemiaNet (ELN; WP8 and WP10) on Standardization of FC in MDS (Amsterdam, The Netherlands, 2008) reported the first steps in defining minimal criteria for the diagnosis and prognostic evaluation of MDS. 6 The current World Health Organization (WHO) 2008 recommendations recognize multiple FC aberrancies (43) in maturation patterns as indicative of MDS. 7 The significance of increased percentages of progenitor cells and expression of CD34 and/or CD117 on these cells is also acknowledged.…”