High sensitivity of the Hematoflow™ solution for chronic myelomonocytic leukemia screening.

BACKGROUND: Accumulation of classical monocytes CD14++ CD16- (also called MO1) ≥ 94% can accurately distinguish chronic myelomonocytic leukemia (CMML) from reactive monocytosis. The HematoFlow™ solution, able to quantify CD16 negative monocytes, could be a useful tool to manage monocytosis which remains a common issue in routine laboratories. METHODS: Classical monocytes were quantified from 153 whole blood samples collected on EDTA using both flow cytometry methods, either MO1 percentage determination by the multiparameter assay previously published and regarded here as the reference method, or CD16 negative monocyte percentage determination by the means of HematoFlow™. RESULTS: Both methods of classical monocyte percentage determination were highly and significantly correlated (r = 0.87, P < 0.0001). The HematoFlow™ solution leant toward an overestimation of the genuine classical monocyte percentages obtained by the reference method. Percentages of CD16 negative monocytes provided by HematoFlow were higher than 94% for all the 73 patients displaying classical monocytes MO1 found ≥94% by the reference method, indicating a sensitivity of 100%. Furthermore, the calculation of CD16 negative monocyte percentage can be easily computerized and integrated to the middleware. CONCLUSIONS: We propose a new application of the Hematoflow™ solution that can be used as a flag system for monocytosis management and CMML detection. © 2017 International Clinical Cytometry Society.

Chronic myelomonocytic leukemia monocytes uniformly display a population of monocytes with CD11c underexpression.

OBJECTIVES: To examine the utility of CD11c expression on monocytes in normal controls and patients with chronic myelomonocytic leukemia (CMML) (n = 23) with flow cytometric immunophenotyping. METHODS: Twenty-three CMML samples and 10 control bone marrows submitted for lymphoma staging without evidence of disease were examined. RESULTS: Monocytes in CMML samples ranged from 4% to 35%. Expression of at least one aberrant monocytic marker was found on the monocytes in 18 (82%) of 22 evaluable cases. The most common aberrancy was underexpression of CD11c (n = 15), while none of the bone marrow controls showed underexpression of CD11c. CONCLUSIONS: A distinct heterogeneous population of monocytic cells with underexpression of CD11c was identified in all these cases. CD11c underexpression was independent of other aberrancies, including HLA-DR underexpression (n = 14), aberrant CD56 expression (n = 11), and underexpression of CD33, CD38, and CD14 (n = 6, 5, and 5, respectively), supporting the utility of CD11c expression status on monocytes in establishing a CMML diagnosis.