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Detection and quantification of beta-2-microglobulin using mass spectrometric immunoassay
K A Tubbs1, D Nedelkov, R W Nelson
1Intrinsic Bioprobes, Inc., 625 South Smith Road, Suite 22, Tempe, Arizona 85281.
Analytical Biochemistry
|February 13, 2001
Summary
A new mass spectrometric immunoassay (MSIA) rapidly and accurately detects beta-2-microglobulin (beta(2)m) in human biofluids. This method shows promise for diagnosing conditions like renal infection by quantifying beta(2)m levels.
Area of Science:
- Biochemistry
- Analytical Chemistry
- Clinical Diagnostics
Background:
- Beta-2-microglobulin (beta(2)m) is a protein found in human biological fluids.
- Accurate and rapid quantification of beta(2)m is crucial for diagnosing various medical conditions, including renal infections.
- Existing methods for beta(2)m detection may lack speed, accuracy, or the ability to differentiate protein variants.
Purpose of the Study:
- To develop and validate a novel mass spectrometric immunoassay (MSIA) for the detection and quantification of beta(2)m in human biological fluids.
- To assess the speed, accuracy, and specificity of the developed MSIA method.
- To demonstrate the clinical applicability of MSIA for beta(2)m analysis using patient samples.
Main Methods:
- Development of affinity pipettor tips functionalized with anti-beta(2)m antibodies for selective isolation and concentration of beta(2)m.
- Utilizing matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for unambiguous detection of beta(2)m.
- Incorporation of an internal standard for quantitative analysis and signal normalization.
Main Results:
- The MSIA method demonstrated rapid analysis times (approx. 15 min per sample) with low nonspecific binding, ensuring interference-free results.
- The assay exhibited a linear dynamic range (R(2) = 0.983) from 0.010-1.0 mg/L with a standard error of ~5%.
- Analysis of urine samples revealed a ~30-fold increase in beta(2)m in a patient with renal infection compared to healthy individuals. The method distinguished between wild-type and glycosylated beta(2)m forms.
Conclusions:
- Mass spectrometric immunoassay (MSIA) provides a rapid, accurate, and sensitive approach for detecting and quantifying beta(2)m in various human biological fluids.
- The developed MSIA method is suitable for clinical applications, including the identification of elevated beta(2)m levels associated with renal infections.
- The ability of MSIA to differentiate beta(2)m variants enhances the precision of wild-type beta(2)m quantification.