Diagnosis and therapeutic regimen
Histopathological examination confirmed that the patients had LCH, as
indicated by positive immunostaining for CD1a and Langerin (CD207) in
the lesion tissues. Patients were divided into single-system (SS) or
multisystem (MS) LCH according to the number of organs or systems
involved and classified as risk organ (RO) positive (liver, spleen,
and/or hematological system) or negative according to the extent of LCH[1].
Patients were treated with a systemic chemotherapy regimen
(CCHG-LCH 2019 protocol,
www.chictr.org.cn, identifier: ChiCTR1900025783), which was based on the
LCH III and LCH-S-2005 protocols10. Briefly, the
first-line treatment was vindesine-steroid combination therapy,
beginning with one or two six-week courses of intensive initial
induction therapy followed by maintenance therapy. The BRAF inhibitor
dabrafenib was given to patients who carried the BRAF -V600E
mutation and had recurrent/refractory LCH disease. The details of the
treatment are shown in the Supplementary Methods.
Mass spectrometry-based
plasma proteomics analysis
We collected diagnostic plasma samples from 11
patients, including 5 with MS
RO+, 6 with SS-LCH and 5 healthy
controls, for proteomic analysis (Supplementary Table S1).
Date-independent acquisition (DIA) combined with liquid
chromatography–tandem mass spectrometry (LC–MS/MS) analysis was
performed. The differentially expressed proteins (DEPs) between MS RO+
LCH and SS LCH were explored. Gene Ontology (GO) and Kyoto Encyclopedia
of Genes and Genomes (KEGG) enrichment analyses were also conducted to
reveal the functions of the DEPs in biological processes.
Single-cell RNA-seq
(sncRNA) analysis
We performed a bioinformatics analysis using a single-cell RNA
sequencing (scRNA-seq) dataset of PBMCs from our previous
study11. Briefly, we divided the samples into two
groups: the MS RO+ LCH group (n = 7) and the SS LCH group (n = 3).
Differentially expressed genes (DEGs) were also analyzed.
ELISA
for plasma sCSF1R in LCH
For patients receiving first-line therapy, plasma samples were collected
at two time points: at the time of diagnosis and at week 6 (after the
first initial induction therapy). For patients receiving dabrafenib
treatment, serial blood samples were collected at every evaluation time
point (baseline, one month, and every three months later) during
follow-up. The levels of sCSF1R were tested using an automated
microplate reader (Thermo, USA) at 450 nm according to the instructions
of the Human CSF1R ELISA Kit (Boster, China).