Publications by authors named "Harshal Abhyankar"

14 Publications

  • Page 1 of 1

Defining the Inflammatory Plasma Proteome in Pediatric Hodgkin Lymphoma.

Cancers (Basel) 2020 Dec 2;12(12). Epub 2020 Dec 2.

Department of Pediatrics, Baylor College of Medicine, Texas Children's Cancer and Hematology Centers, Houston, TX 77030, USA.

Hodgkin lymphoma (HL) histopathology is characterized by rare malignant Reed-Sternberg cells among an inflammatory infiltrate. We hypothesized that characteristics of inflammation in pediatric HL lesions would be reflected by the levels of inflammatory cytokines or chemokines in pre-therapy plasma of children with HL. The study objectives were to better define the inflammatory pre-therapy plasma proteome and identify plasma biomarkers associated with extent of disease and clinical outcomes in pediatric HL. Pre-therapy plasma samples were obtained from pediatric subjects with newly diagnosed HL and healthy pediatric controls. Plasma concentrations of 135 cytokines/chemokines were measured with the Luminex platform. Associations between protein concentration and disease characteristics were determined using multivariate permutation tests with false discovery control. Fifty-six subjects with HL (mean age: 13 years, range 3-18) and 47 controls were analyzed. The cytokine/chemokine profiles of subjects with HL were distinct from controls, and unique cytokines/chemokines were associated with high-risk disease (IL-10, TNF-α, IFN-γ, IL-8) and slow early response (CCL13, IFN-λ1, IL-8). TNFSF10 was significantly elevated among those who ultimately relapsed and was significantly associated with worse event-free survival. These biomarkers could be incorporated into biologically based risk stratification to optimize outcomes and minimize toxicities in pediatric HL.
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http://dx.doi.org/10.3390/cancers12123603DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7761312PMC
December 2020

Overcoming T cell exhaustion in LCH: PD-1 blockade and targeted MAPK inhibition are synergistic in a mouse model of LCH.

Blood 2020 Oct 19. Epub 2020 Oct 19.

1Texas Children's Cancer Center, Texas Children's Hospital, United States.

Langerhans cell histiocytosis (LCH) is an inflammatory myeloid neoplasia characterized by granulomatous lesions containing pathological CD207+ dendritic cells (DCs) with persistent mitogen-activated protein kinase (MAPK) pathway activation. Standard of care chemotherapy strategies is inadequate for most patients with multisystem disease, and optimal strategies for relapsed and refractory disease are not defined. The mechanisms underlying development of inflammation in LCH lesions, the role of inflammation in pathogenesis and potential for immunotherapy are unknown. Analysis of the immune infiltrate in LCH lesions identified the most prominent immune cells as T lymphocytes. Both CD8+ and CD4+ T cells exhibited 'exhausted' phenotypes with high expression of the immune checkpoint receptors. LCH DCs showed robust expression of ligands to checkpoint receptors. Intra-lesional CD8+ T cells showed blunted expression of Tc1/Tc2 cytokines and impaired effector function. In contrast, intra-lesional regulatory T cells (Tregs) demonstrated intact suppressive activity. Treatment of BRAFV600ECD11c LCH mice with anti-PD-1 or MAPK inhibitor reduced lesion size, but with distinct responses: whereas MAPK inhibitor treatment resulted in reduction of the myeloid compartment, anti-PD-1 treatment was associated with reduction in the lymphoid compartment. Notably, combined treatment with MAPK inhibitor and anti-PD-1 significantly decreased both CD8+ T cell and myeloid LCH cells in a synergistic fashion. These results are consistent with a model that MAPK hyperactivation in myeloid LCH cells drives recruitment of functionally exhausted T cells within the LCH microenvironment and highlight combined MAPK and checkpoint inhibition as a potential therapeutic strategy.
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http://dx.doi.org/10.1182/blood.2020005867DOI Listing
October 2020

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

Blood Adv 2020 01;4(1):87-99

Texas Children's Cancer Center, Texas Children's Hospital, Houston, TX.

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.
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http://dx.doi.org/10.1182/bloodadvances.2019000488DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6960472PMC
January 2020

Genetic and mechanistic diversity in pediatric hemophagocytic lymphohistiocytosis.

Blood 2018 07 9;132(1):89-100. Epub 2018 Apr 9.

Department of Pediatrics, Baylor College of Medicine, Houston, TX.

The HLH-2004 criteria are used to diagnose hemophagocytic lymphohistiocytosis (HLH), yet concern exists for their misapplication, resulting in suboptimal treatment of some patients. We sought to define the genomic spectrum and associated outcomes of a diverse cohort of children who met the HLH-2004 criteria. Genetic testing was performed clinically or through research-based whole-exome sequencing. Clinical metrics were analyzed with respect to genomic results. Of 122 subjects enrolled over the course of 17 years, 101 subjects received genetic testing. Biallelic familial HLH (fHLH) gene defects were identified in only 19 (19%) and correlated with presentation at younger than 1 year of age ( < .0001). Digenic fHLH variants were observed but lacked statistical support for disease association. In 28 (58%) of 48 subjects, research whole-exome sequencing analyses successfully identified likely molecular explanations, including underlying primary immunodeficiency diseases, dysregulated immune activation and proliferation disorders, and potentially novel genetic conditions. Two-thirds of patients identified by the HLH-2004 criteria had underlying etiologies for HLH, including genetic defects, autoimmunity, and malignancy. Overall survival was 45%, and increased mortality correlated with HLH triggered by infection or malignancy ( < .05). Differences in survival did not correlate with genetic profile or extent of therapy. HLH should be conceptualized as a phenotype of critical illness characterized by toxic activation of immune cells from different underlying mechanisms. In most patients with HLH, targeted sequencing of fHLH genes remains insufficient for identifying pathogenic mechanisms. Whole-exome sequencing, however, may identify specific therapeutic opportunities and affect hematopoietic stem cell transplantation options for these patients.
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http://dx.doi.org/10.1182/blood-2017-11-814244DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6034641PMC
July 2018

CNS Langerhans cell histiocytosis: Common hematopoietic origin for LCH-associated neurodegeneration and mass lesions.

Cancer 2018 06 6;124(12):2607-2620. Epub 2018 Apr 6.

Texas Children's Cancer Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas.

Background: Central nervous system Langerhans cell histiocytosis (CNS-LCH) brain involvement may include mass lesions and/or a neurodegenerative disease (LCH-ND) of unknown etiology. The goal of this study was to define the mechanisms of pathogenesis that drive CNS-LCH.

Methods: Cerebrospinal fluid (CSF) biomarkers including CSF proteins and extracellular BRAFV600E DNA were analyzed in CSF from patients with CNS-LCH lesions compared with patients with brain tumors and other neurodegenerative conditions. Additionally, the presence of BRAFV600E was tested in peripheral mononuclear blood cells (PBMCs) as well as brain biopsies from LCH-ND patients, and the response to BRAF-V600E inhibitor was evaluated in 4 patients with progressive disease.

Results: Osteopontin was the only consistently elevated CSF protein in patients with CNS-LCH compared with patients with other brain pathologies. BRAFV600E DNA was detected in CSF of only 2/20 (10%) cases, both with LCH-ND and active lesions outside the CNS. However, BRAFV600E PBMCs were detected with significantly higher frequency at all stages of therapy in LCH patients who developed LCH-ND. Brain biopsies of patients with LCH-ND demonstrated diffuse perivascular infiltration by BRAFV600E cells with monocyte phenotype (CD14 CD33 CD163 P2RY12 ) and associated osteopontin expression. Three of 4 patients with LCH-ND treated with BRAF-V600E inhibitor experienced significant clinical and radiologic improvement.

Conclusion: In LCH-ND patients, BRAFV600E cells in PBMCs and infiltrating myeloid/monocytic cells in the brain is consistent with LCH-ND as an active demyelinating process arising from a mutated hematopoietic precursor from which LCH lesion CD207 cells are also derived. Therapy directed against myeloid precursors with activated MAPK signaling may be effective for LCH-ND. Cancer 2018;124:2607-20. © 2018 American Cancer Society.
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http://dx.doi.org/10.1002/cncr.31348DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6289302PMC
June 2018

Activating MAPK1 (ERK2) mutation in an aggressive case of disseminated juvenile xanthogranuloma.

Oncotarget 2017 Jul;8(28):46065-46070

Texas Children's Cancer Center, Texas Children's Hospital, Houston, TX 77030, USA.

Juvenile xanthogranuloma (JXG) is a rare histiocytic disorder that is usually benign and self-limiting. We present a case of atypical, aggressive JXG harboring a novel mitogen-activated protein kinase (MAPK) pathway mutation in the MAPK1 gene, which encodes mitogen-activated protein kinase 1 or extracellular signal-regulated 2 (ERK2). Our analysis revealed that the mutation results in constitutive ERK activation that is resistant to BRAF or MEK inhibitors but susceptible to an ERK inhibitor. These data highlight the importance of identifying specific MAPK pathway alterations as part of the diagnostic workup for patients with histiocytic disorders rather than initiating empiric treatment with MEK inhibitors.
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http://dx.doi.org/10.18632/oncotarget.17521DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5542249PMC
July 2017

Alternative genetic mechanisms of BRAF activation in Langerhans cell histiocytosis.

Blood 2016 11 11;128(21):2533-2537. Epub 2016 Oct 11.

Texas Children's Cancer Center, Texas Children's Hospital, Houston, TX.

Langerhans cell histiocytosis (LCH) is characterized by inflammatory lesions containing pathologic CD207 dendritic cells with constitutively activated ERK. Mutually exclusive somatic mutations in MAPK pathway genes have been identified in ∼75% of LCH cases, including recurrent BRAF-V600E and MAP2K1 mutations. To elucidate mechanisms of ERK activation in the remaining 25% of patients, we performed whole-exome sequencing (WES, n = 6), targeted BRAF sequencing (n = 19), and/or whole-transcriptome sequencing (RNA-seq, n = 6) on 24 LCH patient samples lacking BRAF-V600E or MAP2K1 mutations. WES and BRAF sequencing identified in-frame BRAF deletions in the β3-αC loop in 6 lesions. RNA-seq revealed one case with an in-frame FAM73A-BRAF fusion lacking the BRAF autoinhibitory regulatory domain but retaining an intact kinase domain. High levels of phospho-ERK were detected in vitro in cells overexpressing either BRAF fusion or deletion constructs and ex vivo in CD207 cells from lesions. ERK activation was resistant to BRAF-V600E inhibition, but responsive to both a second-generation BRAF inhibitor and a MEK inhibitor. These results support an emerging model of universal ERK-activating genetic alterations driving pathogenesis in LCH. A personalized approach in which patient-specific alterations are identified may be necessary to maximize benefit from targeted therapies for patients with LCH.
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http://dx.doi.org/10.1182/blood-2016-08-733790DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5123197PMC
November 2016

Primary immunodeficiency diseases: Genomic approaches delineate heterogeneous Mendelian disorders.

Authors:
Asbjørg Stray-Pedersen Hanne Sørmo Sorte Pubudu Samarakoon Tomasz Gambin Ivan K Chinn Zeynep H Coban Akdemir Hans Christian Erichsen Lisa R Forbes Shen Gu Bo Yuan Shalini N Jhangiani Donna M Muzny Olaug Kristin Rødningen Ying Sheng Sarah K Nicholas Lenora M Noroski Filiz O Seeborg Carla M Davis Debra L Canter Emily M Mace Timothy J Vece Carl E Allen Harshal A Abhyankar Philip M Boone Christine R Beck Wojciech Wiszniewski Børre Fevang Pål Aukrust Geir E Tjønnfjord Tobias Gedde-Dahl Henrik Hjorth-Hansen Ingunn Dybedal Ingvild Nordøy Silje F Jørgensen Tore G Abrahamsen Torstein Øverland Anne Grete Bechensteen Vegard Skogen Liv T N Osnes Mari Ann Kulseth Trine E Prescott Cecilie F Rustad Ketil R Heimdal John W Belmont Nicholas L Rider Javier Chinen Tram N Cao Eric A Smith Maria Soledad Caldirola Liliana Bezrodnik Saul Oswaldo Lugo Reyes Francisco J Espinosa Rosales Nina Denisse Guerrero-Cursaru Luis Alberto Pedroza Cecilia M Poli Jose L Franco Claudia M Trujillo Vargas Juan Carlos Aldave Becerra Nicola Wright Thomas B Issekutz Andrew C Issekutz Jordan Abbott Jason W Caldwell Diana K Bayer Alice Y Chan Alessandro Aiuti Caterina Cancrini Eva Holmberg Christina West Magnus Burstedt Ender Karaca Gözde Yesil Hasibe Artac Yavuz Bayram Mehmed Musa Atik Mohammad K Eldomery Mohammad S Ehlayel Stephen Jolles Berit Flatø Alison A Bertuch I Celine Hanson Victor W Zhang Lee-Jun Wong Jianhong Hu Magdalena Walkiewicz Yaping Yang Christine M Eng Eric Boerwinkle Richard A Gibbs William T Shearer Robert Lyle Jordan S Orange James R Lupski

J Allergy Clin Immunol 2017 01 16;139(1):232-245. Epub 2016 Jul 16.

Baylor-Hopkins Center for Mendelian Genomics of the Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Tex; Department of Pediatrics, Baylor College of Medicine, and Texas Children's Hospital, Houston, Tex; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Tex; Human Genome Sequencing Center, Baylor College of Medicine, Houston, Tex. Electronic address:

Background: Primary immunodeficiency diseases (PIDDs) are clinically and genetically heterogeneous disorders thus far associated with mutations in more than 300 genes. The clinical phenotypes derived from distinct genotypes can overlap. Genetic etiology can be a prognostic indicator of disease severity and can influence treatment decisions.

Objective: We sought to investigate the ability of whole-exome screening methods to detect disease-causing variants in patients with PIDDs.

Methods: Patients with PIDDs from 278 families from 22 countries were investigated by using whole-exome sequencing. Computational copy number variant (CNV) prediction pipelines and an exome-tiling chromosomal microarray were also applied to identify intragenic CNVs. Analytic approaches initially focused on 475 known or candidate PIDD genes but were nonexclusive and further tailored based on clinical data, family history, and immunophenotyping.

Results: A likely molecular diagnosis was achieved in 110 (40%) unrelated probands. Clinical diagnosis was revised in about half (60/110) and management was directly altered in nearly a quarter (26/110) of families based on molecular findings. Twelve PIDD-causing CNVs were detected, including 7 smaller than 30 Kb that would not have been detected with conventional diagnostic CNV arrays.

Conclusion: This high-throughput genomic approach enabled detection of disease-related variants in unexpected genes; permitted detection of low-grade constitutional, somatic, and revertant mosaicism; and provided evidence of a mutational burden in mixed PIDD immunophenotypes.
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http://dx.doi.org/10.1016/j.jaci.2016.05.042DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5222743PMC
January 2017

Differentiating skin-limited and multisystem Langerhans cell histiocytosis.

J Pediatr 2014 Nov 21;165(5):990-6. Epub 2014 Oct 21.

Texas Children's Cancer Center, Baylor College of Medicine, Houston, TX.

Objective: To identify features associated with multisystem involvement and therapeutic failure in patients with skin Langerhans cell histiocytosis (LCH).

Study Design: We reviewed medical records of 71 consecutive patients with LCH with skin involvement evaluated at Texas Children's Hospital and analyzed clinical features, laboratory results, and the presence of circulating cells with the BRAF-V600E mutation with respect to initial staging and clinical outcomes.

Results: Skin disease in patients older than 18 months of age at diagnosis was associated with the presence of multisystem disease (OR, 9.65; 95% CI, 1.17-79.4). Forty percent of patients referred for presumed skin-limited LCH had underlying multisystem involvement, one-half of these with risk-organ involvement. Patients with skin-limited LCH had a 3-year progression-free survival of 89% after initial therapy, and none developed multisystem disease. Patients with skin/multisystem involvement had a 3-year progression-free survival of 44% with vinblastine/prednisone therapy, and risk-organ involvement did not correlate with failure to achieve nonactive disease. Circulating cells with BRAF-V600E were detected at higher frequency in patients with multisystem involvement (8 of 11 skin/multisystem vs 1 of 13 skin-limited; P = .002).

Conclusion: Skin-limited LCH necessitates infrequent therapeutic intervention and has a lower risk of progression relative to skin plus multisystem LCH. The less-aggressive clinical course and lack of circulating cells with the BRAF-V600E mutation in skin-limited LCH suggest a different mechanism of disease origin compared with multisystem or risk-organ disease.
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http://dx.doi.org/10.1016/j.jpeds.2014.07.063DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4254414PMC
November 2014

Survivin-specific T cell receptor targets tumor but not T cells.

J Clin Invest 2015 Jan 21;125(1):157-68. Epub 2014 Nov 21.

Survivin is a tumor-associated antigen (TAA) that inhibits apoptosis and is widely overexpressed in cancer cells; therefore, survivin has potential as a target for cancer immunotherapy. Application of HLA-A2-restricted survivin-specific T cell receptors (TCRs) isolated from allogeneic HLA-mismatched TCR repertoires has, however, been impeded by the inability of these TCRs to distinguish healthy cells expressing low levels of survivin from cancer cells with high survivin expression levels. Here, we identified an HLA-A2-restricted survivin-specific TCR isolated from autologous TCR repertoires that targets tumor cells in vitro and in vivo but does not cause fratricidal toxicity. Molecular modeling of the TCR-peptide-HLA ternary complexes and alanine scanning revealed that the autologously derived TCRs had tighter interactions with the survivin peptide than did fratricidal TCRs. Similar recognition patterns were observed among 7 additional TAA-specific TCRs isolated from allogeneic versus autologous repertoires. Together, the results from this study indicate that maximal peptide recognition is key for TCR selectivity and likely critical for reducing unwanted off-target toxicities. Moreover, isolating TCRs from autologous repertoires to maximize TCR selectivity has potential as a useful strategy to identify and select other shared tumor- and self-antigen-specific TCRs and ensure selective antitumor activity.
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http://dx.doi.org/10.1172/JCI75876DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4382259PMC
January 2015

Mutually exclusive recurrent somatic mutations in MAP2K1 and BRAF support a central role for ERK activation in LCH pathogenesis.

Blood 2014 Nov 8;124(19):3007-15. Epub 2014 Sep 8.

Texas Children's Cancer Center, Texas Children's Hospital, Houston, TX; Department of Molecular and Human Genetics, Human Genome Sequencing Center, Division of Pediatric Hematology-Oncology, Department of Pediatrics, Program in Translational Biology and Molecular Medicine, and.

Langerhans cell histiocytosis (LCH) is a myeloproliferative disorder characterized by lesions composed of pathological CD207(+) dendritic cells with an inflammatory infiltrate. BRAFV600E remains the only recurrent mutation reported in LCH. In order to evaluate the spectrum of somatic mutations in LCH, whole exome sequencing was performed on matched LCH and normal tissue samples obtained from 41 patients. Lesions from other histiocytic disorders, juvenile xanthogranuloma, Erdheim-Chester disease, and Rosai-Dorfman disease were also evaluated. All of the lesions from histiocytic disorders were characterized by an extremely low overall rate of somatic mutations. Notably, 33% (7/21) of LCH cases with wild-type BRAF and none (0/20) with BRAFV600E harbored somatic mutations in MAP2K1 (6 in-frame deletions and 1 missense mutation) that induced extracellular signal-regulated kinase (ERK) phosphorylation in vitro. Single cases of somatic mutations of the mitogen-activated protein kinase (MAPK) pathway genes ARAF and ERBB3 were also detected. The ability of MAPK pathway inhibitors to suppress MAPK kinase and ERK phosphorylation in cell culture and primary tumor models was dependent on the specific LCH mutation. The findings of this study support a model in which ERK activation is a universal end point in LCH arising from pathological activation of upstream signaling proteins.
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http://dx.doi.org/10.1182/blood-2014-05-577825DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4224195PMC
November 2014

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

J Exp Med 2014 Apr 17;211(4):669-83. Epub 2014 Mar 17.

Department of Oncological Sciences, 2 Tisch Cancer Institute, and 3 Immunology Institute, Mount Sinai School of Medicine, New York, NY 10029.

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.
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http://dx.doi.org/10.1084/jem.20130977DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3978272PMC
April 2014