title: Evaluation of a new capillary zone electrophoresis system for the identification and typing of Bence Jones Protein.
abstract: OBJECTIVE
  Capillary electrophoresis has recently emerged as a new sensitive technique for the separation of urinary proteins. We evaluated a new method for Bence Jones Protein (BJP) detection and characterization on native urine samples by the Paragon CZE 2000 system. To avoid interference in electrophoretic separation, urine samples were preliminarily treated for the selective removal of interfering salt particles.
  
  
  METHODS
  The evaluation was done on a total of 350 fresh 24-h urine samples. The salt particle removal consisted of a manual chromatographic separation, optimized in the course of our evaluation. Capillary zone urinary protein electrophoresis (CZ-UPE) was compared with conventional high-resolution electrophoresis on an agarose gel, while capillary immunosubtraction (CZU-IFE) was compared with agarose gel immunofixation.
  
  
  RESULTS
  After finding a consistent protein loss in eluates, the preanalytical treatment was optimized by changing sample dilution and eluate collection. The within- and between-run imprecision values for monoclonal peaks corresponding to BJP ranged from 0.4-12.2% to 3.3-6.3%, respectively. The detection limit for BJP, defined as the lowest measurable monoclonal peak on CZ-UPE, was 0.0012 g/L for kappa BJP and 0.0007 g/L for lambda BJP. CZ-UPE and CZU-IFE sensitivities were significantly lower in urine samples with a total protein level < or = 100 mg/L (67% and 78%, respectively) compared to those with total protein >100 mg/L (92% and 94%, respectively). Comparison between BJP measurements obtained from densitometric scanning with those from absorbance tracing showed a correlation coefficient of 0.994 and a bias of 29.8 mg/L.
  
  
  CONCLUSIONS
  Paragon CZE 2000 can be introduced in routine for screening and typing of BJP; in urine samples with a total protein level >100 mg/L, the performance is consistent with results from published validation studies on CZE applied to serum samples.
authors.affiliation: Department of Laboratory Medicine, University Hospital of Padua, Italy.
authors.forename: Michele
authors.initials: M
authors.lastname: Mussap
authors.forename: Silvia
authors.initials: S
authors.lastname: Ponchia
authors.forename: Martina
authors.initials: M
authors.lastname: Zaninotto
authors.forename: Mariacristina
authors.initials: M
authors.lastname: Varagnolo
authors.forename: Mario
authors.initials: M
authors.lastname: Plebani
mesh_terms: D001536:Bence Jones Protein / Q000652:urine*; D004587:Electrophoresis, Agar Gel; D019075:Electrophoresis, Capillary / Q000295:instrumentation / Q000379:methods; D006801:Humans; D012492:Salts / Q000302:isolation & purification; D012680:Sensitivity and Specificity
chemical_list: D012492:Salts; D001536:Bence Jones Protein