Quantification of peptides from immunoglobulin constant and variable regions by LC-MRM MS for assessment of multiple myeloma patients.
OBJECTIVE
Quantitative MS assays for Igs are compared with existing clinical methods in samples from patients with plasma cell dyscrasias, for example, multiple myeloma (MM).


METHODS
Using LC-MS/MS data, Ig constant region peptides, and transitions were selected for LC-MRM MS. Quantitative assays were used to assess Igs in serum from 83 patients. RNA sequencing and peptide-based LC-MRM are used to define peptides for quantification of the disease-specific Ig.


RESULTS
LC-MRM assays quantify serum levels of Igs and their isoforms (IgG1-4, IgA1-2, IgM, IgD, and IgE, as well as kappa (κ) and lambda (λ) light chains). LC-MRM quantification has been applied to single samples from a patient cohort and a longitudinal study of an IgE patient undergoing treatment, to enable comparison with existing clinical methods. Proof-of-concept data for defining and monitoring variable region peptides are provided using the H929 MM cell line and two MM patients.


CONCLUSIONS
LC-MRM assays targeting constant region peptides determine the type and isoform of the involved Ig and quantify its expression; the LC-MRM approach has improved sensitivity compared with the current clinical method, but slightly higher inter-assay variability. Detection of variable region peptides is a promising way to improve Ig quantification, which could produce a dramatic increase in sensitivity over existing methods, and could further complement current clinical techniques.
Molecular Oncology and Proteomics, Moffitt Cancer Center, Tampa, FL, USA.
Elizabeth R
ER
Remily-Wood
Kaaron
K
Benson
Rachid C
RC
Baz
Y Ann
YA
Chen
Mohamad
M
Hussein
Monique A
MA
Hartley-Brown
Robert W
RW
Sprung
Brianna
B
Perez
Richard Z
RZ
Liu
Sean J
SJ
Yoder
Jamie K
JK
Teer
Steven A
SA
Eschrich
John M
JM
Koomen
D000595:Amino Acid Sequence; D002853:Chromatography, Liquid; D015331:Cohort Studies; D006801:Humans; D007127:Immunoglobulin Constant Regions / Q000097:blood* / Q000737:chemistry; D007135:Immunoglobulin Variable Region / Q000097:blood* / Q000737:chemistry; D008969:Molecular Sequence Data; D009101:Multiple Myeloma / Q000097:blood*
D007127:Immunoglobulin Constant Regions; D007135:Immunoglobulin Variable Region
Ig quantification; LC-MRM MS; Multiple myeloma