BRAF-V600E expression in precursor versus differentiated dendritic cells defines clinically distinct LCH risk groups

J Exp Med. 2014 Apr 7;211(4):669-83. doi: 10.1084/jem.20130977. Epub 2014 Mar 17.


Langerhans cell histiocytosis (LCH) is a clonal disorder with elusive etiology, characterized by the accumulation of CD207(+) dendritic cells (DCs) in inflammatory lesions. Recurrent BRAF-V600E mutations have been reported in LCH. In this study, lesions from 100 patients were genotyped, and 64% carried the BRAF-V600E mutation within infiltrating CD207(+) DCs. BRAF-V600E expression in tissue DCs did not define specific clinical risk groups but was associated with increased risk of recurrence. Strikingly, we found that patients with active, high-risk LCH also carried BRAF-V600E in circulating CD11c(+) and CD14(+) fractions and in bone marrow (BM) CD34(+) hematopoietic cell progenitors, whereas the mutation was restricted to lesional CD207(+) DC in low-risk LCH patients. Importantly, BRAF-V600E expression in DCs was sufficient to drive LCH-like disease in mice. Consistent with our findings in humans, expression of BRAF-V600E in BM DC progenitors recapitulated many features of the human high-risk LCH, whereas BRAF-V600E expression in differentiated DCs more closely resembled low-risk LCH. We therefore propose classification of LCH as a myeloid neoplasia and hypothesize that high-risk LCH arises from somatic mutation of a hematopoietic progenitor, whereas low-risk disease arises from somatic mutation of tissue-restricted precursor DCs.

Publication types

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

MeSH terms

  • Animals
  • Antigens, CD34 / metabolism
  • Antigens, Surface / metabolism
  • Bone Marrow / pathology
  • CD11c Antigen / metabolism
  • Cell Differentiation*
  • Cell Lineage
  • Child
  • Child, Preschool
  • Dendritic Cells / metabolism*
  • Female
  • Genetic Predisposition to Disease*
  • Hematopoietic Stem Cells / metabolism
  • Histiocytosis, Langerhans-Cell / blood
  • Histiocytosis, Langerhans-Cell / genetics*
  • Histiocytosis, Langerhans-Cell / pathology*
  • Histocompatibility Antigens Class II / metabolism
  • Humans
  • Infant
  • Lectins, C-Type / metabolism
  • Male
  • Mannose-Binding Lectins / metabolism
  • Mice
  • Mutation / genetics*
  • Phenotype
  • Proto-Oncogene Proteins B-raf / genetics*
  • Risk Factors
  • Treatment Outcome


  • Antigens, CD34
  • Antigens, Surface
  • CD11c Antigen
  • Cd207 protein, mouse
  • Histocompatibility Antigens Class II
  • Lectins, C-Type
  • Mannose-Binding Lectins
  • BRAF protein, human
  • Proto-Oncogene Proteins B-raf