Targeting interferon alpha subtypes in serum: a comparison of analytical approaches to the detection and quantitation of proteins in complex biological matrices.
The targeted detection and quantitation of proteins in complex biological fluids such as blood is as analytically challenging as it is crucial for biomedical research. Antibody-based techniques such as the ELISA are the current standards for such measurements, having in favorable cases high specificity and pg/mL detection limits. Long development timelines and susceptibility to cross reactivity have led researchers to investigate mass spectrometric alternatives. The literature contains diverse schemes for sample preparation and multiple platforms for mass spectrometric detection. Critical evaluations of competing technologies are, however, badly needed. Taking closely related subtypes of the pro-inflammatory cytokine interferon alpha as a test case, we compared a sample preparation workflow based on affinity enrichment to one based on generic multidimensional chromatography, and evaluated mass spectrometric techniques using tandem mass spectrometry on low resolution ion traps, high resolution "accurate mass tags," and triple quadrupole selective reaction monitoring. Each workflow and detection method proved capable of detecting and discriminating between these proteins at or below the ng/mL level in human serum. Quantitation by isotope dilution was evaluated using full length protein as the internal standard. Both triple quadrupole selected reaction monitoring and orbitrap selected ion monitoring produced linear calibration curves from 1 ng/mL to 1 microg/mL, with lower limits of quantitation below 5 and 50 ng/mL, respectively.
Izrael-Tomasevic
Anita
A
Protein Chemistry Department, Genentech Inc., South San Francisco, California 94080, USA.
Phu
Lilian
L
Phung
Qui T
QT
Lill
Jennie R
JR
Arnott
David
D
D002138:Calibration; D002852:Chromatography, Ion Exchange; D006801:Humans; D016898:Interferon-alpha / Q000097:blood*; D007553:Isotope Labeling; D016014:Linear Models; D013058:Mass Spectrometry / Q000379:methods*; D012680:Sensitivity and Specificity
D016898:Interferon-alpha