Bone marrow-derived myeloid progenitors as driver mutation carriers in high- And low-risk Langerhans cell histiocytosis

Yanling Xiao*, Astrid G.S. Van Halteren*, Xin Lei, Jelske Borst, Eline Steenwijk, Tom De Wit, Joanna Grabowska, Rhianne Voogd, Paul Kemps, Jennifer Picarsic, Cor Van den Bos, Jannie Borst*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

20 Citations (Scopus)

Abstract

Langerhans cell histiocytosis (LCH) is a myeloid neoplasia, driven by sporadic activating mutations in the MAPK pathway. The misguided myeloid dendritic cell (DC) model proposes that high-risk, multisystem, risk-organ-positive (MS-RO+) LCH results from driver mutation in a bone marrow (BM)-resident multipotent hematopoietic progenitor, while low-risk, MS-RO2 and single-system LCH would result from driver mutation in a circulating or tissue-resident, DC-committed precursor. We have examined the CD34+c-Kit+Flt3+ myeloid progenitor population as potential mutation carrier in all LCH disease manifestations. This population contains oligopotent progenitors ofmonocytes (Mo's)/macrophages (MFs), osteoclasts (OCs), and DCs. CD34+c-Kit+Flt3+ cells from BM of MS-RO+ LCH patients produced Langerhans cell (LC)-like cells in vitro. Both LC-like and DC offspring from this progenitor carried the BRAF mutation, confirming their common origin. In both high- and low-risk LCH patients, CD34+c-Kit+Flt3+ progenitor frequency in blood was higher than in healthy donors. In oneMS-RO+ LCHpatient, CD34+c-Kit+Flt3+ cell frequency in blood and its BRAF-mutated offspring reported response to chemotherapy. CD34+c-Kit+Flt3+ progenitors from blood of both high- and low-risk LCH patients gave rise to DCs and LC-like cells in vitro, but the driver mutation was not easily detectable, likely due to low frequency of mutated progenitors. Mutant BRAF alleles were found in Mo's /MFs, DCs, LC-like cells, and/or OC-like cells in lesions and/or Mo and DCs in blood of multiple low-risk patients.We therefore hypothesize that in both high- and low-risk LCH, the driver mutation is present in a BM-resident myeloid progenitor that can be mobilized to the blood.

Original languageEnglish
Pages (from-to)2188-2199
Number of pages12
JournalBlood
Volume136
Issue number19
DOIs
Publication statusPublished - 5 Nov 2020
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2020 by The American Society of Hematology.

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