Simple method for quantification of Bence Jones proteins.
BACKGROUND
Quantification of free monoclonal light chains in urine [Bence Jones proteins (BJPs)] is used to diagnose multiple myeloma and to evaluate response to treatment. We have developed and evaluated an optimized approach for quantification of BJPs.


METHODS
High-resolution gel electrophoresis of unconcentrated urine and albumin calibrators was carried out on Sebia's Hydrasys instrument with Hydragel HR agarose gels. After staining with acid violet, the gels were scanned densitometrically. The staining intensities of BJP bands relative to the staining intensities of albumin solutions were used to determine the BJP concentrations. Results for patient samples were compared with conventional agarose gel electrophoresis on concentrated samples.


RESULTS
The relationships between staining intensity and the protein concentrations of albumin and BJPs were linear up to protein concentrations of approximately 2000 mg/L. The detection limit was approximately 20 mg/L. The interassay imprecision (CV) was approximately 8% (n = 23, duplicate analysis), and the results (y) showed a close positive relationship to the comparison method: slope = 0.82 (confidence interval, 0.75-0.88); y-intercept = 34 (-14 to 81) mg/L; n = 29; r(2) = 0.96.


CONCLUSIONS
Agarose gel electrophoresis of unconcentrated urine samples together with a series of albumin calibrators followed by acid violet staining and densitometric scanning is sufficiently reproducible and sensitive to quantify clinically relevant BJPs.
Salomo
Morten
M
Departments of Hematology, Rigshospitalet, University of Copenhagen, Blegdamsvej 9, DK-2100 Copenhagen, Denmark.
Gimsing
Peter
P
Nielsen
Lars B
LB
D001536:Bence Jones Protein / Q000652:urine*; D004587:Electrophoresis, Agar Gel / Q000379:methods; D006801:Humans; D009101:Multiple Myeloma / Q000175:diagnosis*; D015203:Reproducibility of Results; D013194:Staining and Labeling
D001536:Bence Jones Protein