Page 124 - Haematologica April 2020

N. van Leeuwen-Kerkhoff et al.
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Figure 2. Classical monocytes are clonally involved and the presence of thrombomodulin correlates with disease states. (A) Sorted cells, including B cells and CD34+ blast cells, from patients with a known cytogenetic aberrancy were subjected to fluorescence in situ hybridization (FISH) analysis. Furthermore, whole bone marrow (BM) samples were used for degree of cytogenetic load. Representative interphase cells hybridized with the chromosome 5q probe, showing loss of 5q in CD34+ blasts and monocytes, and no loss of 5q in B cells. In three tested cases (monosomy 7, deletion 5q and trisomy 8), classical monocytes and CD34+ blast cells were highly involved in the dysplastic clone, whereas B cells were not involved. Interphase FISH on whole BM samples showed both an aberrant and a normal cell line. (B) Thrombomodulin- positive (TM+) classical monocytes in different myelodysplastic syndrome (MDS) risk groups defined according to the Revised International Prognostic Scoring System and the World Health Organization (WHO) 2016 classification. The percentage of classical monocytes that express TM was highest in the very low/low-risk groups: the percentage of TM expression was significantly reduced in higher-risk groups compared to the lower-risk group [mean ± standard error of mean (SEM): normal BM (n=25) 11.3% ± 3.0% vs. very low/low-risk MDS BM (n=54) 40.1% ± 2.9% vs. intermediate-risk MDS BM (n=22) 22.7% ± 3.7% vs. high/very high-risk MDS BM (n=16) 28.3% ± 4.9%). Patients with low-risk MDS according to the WHO 2016 classification (single/multiple lineage dysplasia with or without ring sideroblasts, n=87) had higher per- centages of TM expression on monocytes (40.9% ± 2.3%) compared to patients in higher-risk groups (excess blasts-1 and -2, n=42) (24.2% ± 2.7%) and normal BM (n=25) (11.3% ± 3.0%). (C) Percentages of classical monocytes that are positive for TM in patients with low and higher blast counts. The percentage of monocytes expressing TM was significantly higher in the group of patients with blast counts below 5% (n=97) than in the group of patients with blast counts ≥5% (n=44) (blast count <5%, 41.3% ± 2.2% vs. blast count ≥5%, 25.7% ± 2.8%). Patients with ring sideroblasts (RS) (n=40) had higher percentages of TM+ monocytes than patients who did not have RS (n=106) (RS yes, 45.4% ± 3.7% vs. RS no, 33.2% ± 2.0%). *P<0.05, **P<0.01, ***P<0.001, ****P<0.0001. IPSS-R: Revised International Prognostic Scoring System; NBM: normal bone marrow; SLD: single lineage dysplasia; MLD: multilineage dysplasia;.RS: ring sideroblasts; EB, excess blasts.
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