Performance of the Sebia CAPILLARYS 2 for detection and immunotyping of serum monoclonal paraproteins

We evaluated the performance of the CAPILLARYS 2 (Sebia, Norcross, GA) capillary electrophoresis system for detection and identification of monoclonal proteins in serum samples. We analyzed 104 serum specimens by Sebia Hydragel serum protein electrophoresis (agarose gel electrophoresis [AGE]/immunofixation electrophoresis [IFE]) and CAPILLARYS 2 capillary zone electrophoresis (CZE)/immunosubtraction. AGE and CZE had sensitivities of 90% and 81%, respectively, based on IFE as the "gold standard," and all bands detected were confirmed by IFE (100% specificity). AGE and CZE had an overall agreement of 91% on serum protein electrophoresis. In the population tested, IgG was detected in 29% of samples by IFE and 30% using immunosubtraction. Similarly IgA was detected in 9% of cases by IFE and 8% by immunosubtraction. IgM and light chains were detected in 6% and 3% of cases, respectively, by IFE, whereas CZE/immunosubtraction did not detect any IgM or light chains. In our hands, AGE and CZE had the same specificity for detection of monoclonal proteins; however, CZE/immunosubtraction seems to be less sensitive than IFE for the detection of IgM and, possibly, serum light chains.

Capillary electrophoresis and the clinical laboratory

Over the past 15 years, CE as an analytical tool has shown great promise in replacing many conventional clinical laboratory methods, such as electrophoresis and HPLC. CE's appeal was that it was fast, used very small amounts of sample and reagents, was extremely versatile, and was able to separate large and small analytes, whether neutral or charged. Because of this versatility, numerous methods have been developed for analytes that are of clinical interest. Other than molecular diagnostic and forensic laboratories CE has not been able to make a major impact in the United States. In contrast, in Europe and Japan an increasing number of clinical laboratories are using CE. Now that automated multicapillary instruments are commercially available along with cost-effective test kits, CE may yet be accepted as an instrument that will be routinely used in the clinical laboratories. This review will focus on areas where CE has the potential to have the greatest impact on the clinical laboratory. These include analyses of proteins found in serum and urine, hemoglobin (A1c and variants), carbohydrate-deficient transferrin, forensic and therapeutic drug screening, and molecular diagnostics.

Advances in Serum Protein Electrophoresis

A major advance in serum protein electrophoresis in the last decade has been the introduction of capillary zone electrophoresis (CZE). Two dedicated automated multichannel instruments for serum protein separation by CZE in clinical laboratories are available, the Paragon CZE 2000 (Beckman Coulter, CA) and the Capillarys (Sebia, France). This chapter focuses on the performance of these commercial multichannel CZE systems. Following topics are addressed: precision, comparison of CZE with gel-based methods, dysproteinemia analysis by CZE, detection and identification of monoclonal proteins by CZE, quality control, and interferences. Examples of electrophoretic patterns are given.

Separation of serum proteins by automated capillary zone electrophoresis

Capillary zone electrophoresis (CZE) of serum proteins is increasingly gaining impact in clinical laboratories. Two automated multichannel instruments dedicated to the separation of serum proteins have become available over the last 6 years, the Paragon CZE 2000 (Beckman Coulter, CA, USA) and, more recently, the Capillarys (Sebia, France). This review focuses on the performance of these commercial instruments to separate serum proteins in a clinical laboratory setting. The utility of CZE to recognize various dysproteinemias and to detect and identify monoclonal proteins will be described and systematically reviewed. The reader will be provided with a summation and an understanding of CZE-specific interference.