Circulating CD1c+ myeloid dendritic cells are potential precursors to LCH lesion CD1a+CD207+ cells

Blood Adv. 2020 Jan 14;4(1):87-99. doi: 10.1182/bloodadvances.2019000488.


Langerhans cell histiocytosis (LCH) is a myeloproliferative disorder that is characterized by the inflammatory lesions with pathogenic CD1a+CD207+ dendritic cells (DCs). BRAFV600E and other somatic activating MAPK gene mutations have been identified in differentiating bone marrow and blood myeloid cells, but the origin of the LCH lesion CD1a+CD207+ DCs and mechanisms of lesion formation remain incompletely defined. To identify candidate LCH CD1a+CD207+ DC precursor populations, gene-expression profiles of LCH lesion CD1a+CD207+ DCs were first compared with established gene signatures from human myeloid cell subpopulations. Interestingly, the CD1c+ myeloid DC (mDC) gene signature was most enriched in the LCH CD1a+CD207+ DC transcriptome. Additionally, the BRAFV600E allele was not only localized to CD1a+CD207- DCs and CD1a+CD207+ DCs, but it was also identified in CD1c+ mDCs in LCH lesions. Transcriptomes of CD1a+CD207- DCs were nearly indistinguishable from CD1a+CD207+ DCs (both CD1a+CD207low and CD1a+CD207high subpopulations). Transcription profiles of LCH lesion CD1a+CD207+ DCs and peripheral blood CD1c+ mDCs from healthy donors were compared to identify potential LCH DC-specific biomarkers: HLA-DQB2 expression was significantly increased in LCH lesion CD1a+CD207+ DCs compared with circulating CD1c+ mDCs from healthy donors. HLA-DQB2 antigen was identified on LCH lesion CD1a+CD207- DCs and CD1a+CD207+ DCs as well as on CD1c+(CD1a+CD207-) mDCs, but it was not identified in any other lesion myeloid subpopulations. HLA-DQB2 expression was specific to peripheral blood of patients with BRAFV600E+ peripheral blood mononuclear cells, and HLA-DQB2+CD1c+ blood cells were highly enriched for the BRAFV600E in these patients. These data support a model in which blood CD1c+HLA-DQB2+ mDCs with activated ERK migrate to lesion sites where they differentiate into pathogenic CD1a+CD207+ DCs.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antigens, CD / genetics
  • Antigens, CD1 / genetics
  • Biomarkers
  • Dendritic Cells
  • Glycoproteins
  • Histiocytosis, Langerhans-Cell* / diagnosis
  • Histiocytosis, Langerhans-Cell* / genetics
  • Humans
  • Lectins, C-Type / genetics
  • Leukocytes, Mononuclear*
  • Mannose-Binding Lectins / genetics
  • Myeloid Cells


  • Antigens, CD
  • Antigens, CD1
  • Biomarkers
  • CD1C protein, human
  • CD207 protein, human
  • Glycoproteins
  • Lectins, C-Type
  • Mannose-Binding Lectins