Primate Monocytes - CD14, CD16 - Ziegler-Heitbrock

Flow cytometric monocyte repartition demonstrates overlap between chronic myelomonocytic leukaemia and myeloid neoplasms with monocytosis.

Abstract

Sir, Chronic myelomonocytic leukaemia (CMML) is a clonal myeloid malignancy resulting in both myelodysplastic and myeloproliferative features with risk of progression to acute myeloid leukaemia (AML).1 Current diagnostic criteria for CMML require persistent monocytosis of
1.0109/L with monocytes accounting for
10% of leukocytes, <20% blasts in the peripheral blood and bone marrow, and either dysplasia involving
1 myeloid lineages or demonstration of an acquired, clonal cytogenetic or molecular abnormality.2 Challenges remain in the diagnosis of CMML given the subjective nature of dysplasia and lack of a definitive cytogenetic or molecular abnormality. The CMML diagnostic criteria of the World Health Organization do not include specific immunophenotypic results. In 2015 Selimoglu-Buet et al.3 published a flow cytometry method using peripheral blood samples for the diagnosis of CMML, termed flow cytometric monocyte repartition (FMR). FMR categorises monocytes into classical, intermediate and non-classical subtypes. An excess of classical monocytes (CD14þ/CD16e; Mo1) or conversely a reduction in intermediate (CD14þ/CD16þ; Mo2) or non-classical monocytes (CD14e/CD16þ; Mo3) reportedly provides a sensitivity and specificity >90%.3 FMR could potentially help select individuals in whom a bone marrow biopsy should be performed, but less is known about FMR in the bone marrow and whether it can distinguish between CMML and other myeloid neoplasms with monocytosis.