Comparison Of Cze With Hrage

Chapter 4 discussed the classification of serum protein dyscrasias using CZE and HRAGE. This chapter covers paraproteinemia and the comparison of CZE vs HRAGE. CZE appears to offer an alternative to HRAGE for the detection of paraproteinemias in serum. When we used the Paragon CZE 2000, we obtained a 100% concordance between CZE and HRAGE in the detection of monoclonal gammopathies (3). However this was only when the paraproteins were within the detection limits of HRAGE: IgG 0.5 g/L, IgA 0.75 g/L, and IgM 0.75 g. In instances when the paraprotein band falls within the transferrin band it is sometimes difficult to identify by HRAGE. However, with CZE it is usually obvious due to a separate peak being seen along side the transferrin band. As discussed in Chapter 4, with computer accusation of the data it is possible to magnify specific areas in the electropheorgram making it is possible to see the separate banding. (Fig. 1A-E)

In a recent study of 1,518 serum samples CZE detected a MC protein in 204 CZE patterns vs 195 by HRAGE (4). It was reported that the increased sensitivity of CZE as a screening test was due to the detection of 3 IgA M

I im

Electrophoresis Pattern Paraproteinemia
Fig. 1. (A) Agarose vs CZE patterns of an IgG lambda monoclonal gammopathy. (B) Agarose vs CZE patterns of an IgA kappa monoclonal gammopathy. (C) Agarose vs CZE patterns of an IgM kappa monoclonal gammopathy.

proteins in the beta region, 4 small monoclonal free light chains and 4 small M proteins superimposed on a polyclonal background. None of these were seen on HRAGE, giving sensitivities for CZE and HRAGE of 95% and 91%, respectively.

Paragon Capillary ElectrophoresisPolyclonal Gammopathy ElectrophoresisBiclonal Gammopathy

Fig. 1. (continued) (D) Agarose vs CZE patterns of a biclonal IgG kappa gammopathy. (E) Agarose vs. CZE of an acute inflammatory pattern with a pseudomonoclonal gammopathy that is identified as C-reactive protein.

Heskens et al. (5) used the Beckman Coulter P/ACE 5000 system to detect 70 of 74 MC proteins as detected by agarose gel electrophoresis. Similar results were seen by Bossuyt et al. (6) who looked at 58 serums that had been previously identified as having an M component. They detected MC proteins in 93% of the serums using Beckman Coulter's Paragon CZE 2000 unit compared to 74% by cellulose acetate electrophoresis and 86% by HRAGE. Clark et al. (7) also examined 305 serum samples for the presence of a monoclonal gammopathy using the Beckman P/ACE 5510 unit and compared the results with those found by HRAGE. They found that CZE detected 100% of the paraproteins detected by HRAGE.

Jenkins et al. (7) were able to correctly identify all 76 paraproteinemic samples, previously identified by HRAGE, using an Applied BioSystems CZE unit. They claimed that the CZE procedure was more sensitive in the detection of IgA paraproteins in the beta region. However, two cases of an IgM paraproteinemia were not detected by their procedure that were identi fied by HRAGE. In another report by Jenkins et al. (9) the results obtained by CZE and HRAGE were compared for 1000 clinical specimens that contained 362 specimens containing monoclonal proteins whose concentrations ranged from 1 to 71 g/L. They found a correlation of 0.96 between HRAGE and CZE. In this case three IgA M proteins were detected by CZE but not by HRAGE because of their presence in the transferrin band. However, two IgM monoclonal bands were detected by HRAGE but not by CZE. In addition, one of 11 light chains was not detected by CZE.

Doleman et al. (10) in a study of 250 outpatients reported excellent concordance between HRAGE and CZE. However, 19 patients had an IgM paraprotein that was not detected by CZE. Once identified by HRAGE, however, the paraproteins were visible on the CZE electrophorogram. This implies that there is a steep learning curve in CZE interpretation that must occur before it can be used as an alternative to HRAGE in the clinical laboratory.

It is evident from the published data that CZE offers an excellent alternative to HRAGE for the screening of serum samples to detect paraproteinemia. However, one must realize that any one method may not be acceptable as a final interpretative procedure for paraproteinemia. Reliance on a back-up procedure, such as immunofixation electrophoresis, HRAGE, polyacryla-mide gel electrophoresis, and two-dimensional electrophoresis, may be necessary for the study of any paraprotein.

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