Monocyte subsets to differentiate chronic myelomonocytic leukemia from reactive monocytosis

Real world implementation of flow cytometric monocyte subset partitioning for distinguishing chronic myelomonocytic leukaemia from other causes of monocytosis

Monocyte subset partitioning by flow cytometry may be a useful tool in distinguishing chronic myelomonocytic leukaemia (CMML) from other causes of monocytosis, however there has been varying success in real world implementation. Additionally, current assays require an individual tube for analysis despite significant overlap in antibodies used in routine T and NK cell analysis. The objective of this study was to validate a flow cytometry assay for the enumeration of monocyte subsets in our community-based laboratory and compare this to a hybrid panel allowing analysis of monocytes, T cells and NK cells in a single tube. Monocyte subset analysis was performed on peripheral blood samples of patients with monocytosis at the time of bone marrow biopsy or transient monocytosis in the setting of bacteraemia. Cut-offs of >94% classical and <1.13% non-classical monocytes for distinguishing CMML were assessed. Classical monocytes were significantly higher, and non-classical monocytes significantly lower in CMML compared to other causes of monocytosis. The sensitivity and specificity of >94% classical monocytes were 73% [95% confidence interval (CI) 43-90%] and 89% (95% CI 75-96%) regardless of which panel was used. Non-classical monocytes of <1.13% had a sensitivity and specificity of 82% (95% CI 52-97%) and 83% (95% CI 68-92%) with the monocyte panel and 55% (95% CI 28-78%) and 89% (95% CI 75-96%) using the hybrid panel. We have found the estimation of the classical monocyte subset to be the most robust and repeatable variation of this assay with sensitivity and specificity that is clinically useful. A hybrid panel may provide an effective approach to implementing monocyte subsets into practice.

Cytokines in the mechanisms of regulation of monocytopoiesis in ischemic heart disease

Introduction. The relationship of the violation of the subpopulation composition of blood monocytes in ischemic cardiomyopathy (ICMP) with changes in monocytopoiesis, as well as the effect of colony-stimulating factor of macrophages (M-CSF) and cytokines on the differentiation of monocytes of various immunophenotypes in the bone marrow is of great relevance.

Aim – to study the role of cytokines in the mechanisms of local and distant regulation of differentiation of classical, intermediate, non-classical and transitional bone marrow monocytes in combination with the content of VEGFR2+-monocytes and hypoxia-induced factor-1a (HIF-1a) in the blood of patients with ischemic heart disease (IHD), suffering and not suffering from ischemic cardiomyopathy.

Materials and methods. Seventy-four patients with IHD, suffering and not suffering from ICMP (30 and 44 people, respectively) were examined. The number of subpopulations of classical (CD14++CD16–), intermediate (CD14++CD16+), nonclassical (CD14+CD16++) and transitional (CD14+CD16–) monocytes (in bone marrow samples) and CD14+VEGFR2+-monocytes (in blood and bone marrow) was determined by flow cytofluorimetry; the concentration of cytokines IL-10, IL-13, TNF-α, IFN-γ, M-CSF in bone marrow and blood, as well as HIF-1a in the blood, was determined by ELISA.

Results. Content of hematopoietins IL-10, IL-13, TNF-α, M-CSF in the bone marrow, as well as the ability of M-CSF to activate and IL-13 to inhibit the differentiation of classical monocytes from transitional cell forms were comparable between groups of patients with IHD. In the blood of patients with ICMP the concentration of IL-10 was higher, and the content of HIF-1α and CD14+VEGFR2+-cells was lower than in patients with IHD without ICMP (IL-10 – 30.00 (26.25–34.50) pg/ mL vs. 0 (23.0–28.0) pg/mL, p < 0.05; HIF-1α – 0.040 (0.029–0.053) ng/mL vs. 0.063 (0.054–0.122) ng/mL, p < 0.05; CD14+VEGFR2+ – 7.00 (5.67–7.15) % vs. 7.80 (7.23–8.17) %, p < 0.05). A feature of monocytopoiesis in ICMP compared with patients with IHD without ICMP is a high concentration of IFN-γ in the BM and a low ratio of M-CSF/IL-13 (10.00 (0.65–18.23) and 0.02 [0–0.15) pg/mL, p < 0.001; 1.02 (0.41–2.00) and 9.00 (2.13–22.09), p < 0.05, respectively), in association with a decrease in the number of classical, intermediate monocytes and an increase in the number of transitional cells in the BM in patients with ICMP relative to patients without cardiomyopathy (21.0 (19.5–23.0) and 47 (41–61.5) %, p < 0.001; 0.3 (0.0–1.2) and 18.5 (6.5–28.0) %, p < 0.01; 76.2 (73.0–78.5) and 30.5 (13.0–41.5) %, p < 0.001, respectively). At the same time, regardless of the clinical form of IHD, IL-10 and IL-13 are distant hematopoietins, TNF-α is local hematopoietin.

Conclusion. An increase in the concentration of IFN-γ and a low ratio of M-CSF/IL-13 in the bone marrow, as well as an excess of IL-10 and a lack of HIF-1a and CD14+VEGFR2+-cells in the blood of IHD patients, are associated with inhibition of differentiation of mature forms of monocytes and the development of ICMP.

Monocyte subsets to differentiate chronic myelomonocytic leukemia from reactive monocytosis

Background

Chronic myelomonocytic leukemia (CMML) is characterized by persistent monocytosis and dysplastic features of blood cells. No specific genetic abnormalities are present in CMML, and reactive monocytosis should be excluded. An increase in classical monocytes (MO1) has been suggested as a screening tool for CMML.

Methods

We evaluated monocyte subsets in the peripheral blood of patients with CMML (n = 16), patients with reactive monocytosis (n = 19), and normal controls (n = 15) with flow cytometry using antibodies against CD14, CD16, CD56, CD24, CD45, and CD2. The cutoff of MO1 ≥94% was validated, and the optimal cutoff was analyzed with receiver operating curve analysis.

Results

The sensitivity of monocyte subset testing for screening for CMML was 0.938 (0.717‐0.997), and the specificity was 0.882 (0.734 ‐ 0.953) using the cutoff of MO1 ≥94%. Serial samples from patients who responded to hypomethylating therapy showed an MO1 < 94%. However, few patients with reactive monocytosis, including patients with nonhematologic malignancies and acute myeloid leukemia, showed an increase in the MO1 ≥ 94%. Monocyte subset results were correlated with the response to hypomethylating therapy in follow‐up samples.

Conclusion

Monocyte subset analysis is useful in screening for and monitoring CMML. Harmonization of the protocols for monocyte subset analysis is required.