Biology and prognostic impact of clonal plasmacytoid dendritic cells in chronic myelomonocytic leukemia

Leukemia. 2019 Oct;33(10):2466-2480. doi: 10.1038/s41375-019-0447-3. Epub 2019 Mar 20.


Islands of CD123high cells have been commonly described in the bone marrow of patients with chronic myelomonocytic leukemia (CMML). Using a multiparameter flow cytometry assay, we detected an excess of CD123+ mononucleated cells that are lineage-negative, CD45+, CD11c-, CD33-, HLA-DR+, BDCA-2+, BDCA-4+ in the bone marrow of 32/159 (20%) patients. Conventional and electron microscopy, flow cytometry detection of cell surface markers, gene expression analyses, and the ability to synthesize interferon alpha in response to Toll-like receptor agonists identified these cells as bona fide plasmacytoid dendritic cells (pDCs). Whole-exome sequencing of sorted monocytes and pDCs identified somatic mutations in genes of the oncogenic RAS pathway in the two cell types of every patient. CD34+ cells could generate high amount of pDCs in the absence of FMS-like tyrosine kinase 3-ligand (FLT3L). Finally, an excess of pDCs correlates with regulatory T cell accumulation and an increased risk of acute leukemia transformation. These results demonstrate the FLT3L-independent accumulation of clonal pDCs in the bone marrow of CMML patients with mutations affecting the RAS pathway, which is associated with a higher risk of disease progression.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aged, 80 and over
  • Antigens, CD / metabolism
  • Biomarkers / metabolism
  • Bone Marrow / metabolism
  • Bone Marrow / pathology
  • Dendritic Cells / metabolism
  • Dendritic Cells / pathology*
  • Female
  • Humans
  • Leukemia, Myelomonocytic, Chronic / metabolism
  • Leukemia, Myelomonocytic, Chronic / pathology*
  • Male
  • Membrane Proteins / metabolism
  • Prognosis
  • T-Lymphocytes, Regulatory / metabolism
  • T-Lymphocytes, Regulatory / pathology


  • Antigens, CD
  • Biomarkers
  • Membrane Proteins
  • flt3 ligand protein