Am J Clin Pathol 2007;128:293-299 293
© American Society for Clinical Pathology
Immunopathology / SEBIA CAPILLARYS 2 PARAPROTEIN DETECTION
Performance of the Sebia CAPILLARYS 2 for Detection
and Immunotyping of Serum Monoclonal Paraproteins
Zhaohai Yang, MD, PhD, Keith Harrison, MD, Yara A. Park, MD, Carolyn H. Chaffin,
Beatrice Thigpen, Pattye L. Easley, John A. Smith, MD, PhD, C. Andrew Robinson, PhD,
Robin G. Lorenz, MD, PhD, and Robert W. Hardy, PhD
Key Words: Capillary zone electrophoresis; Monoclonal proteins; Immunotyping; Immunofixation electrophoresis; Serum protein
A b s t r a c t
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.
Plasma cell myeloma is a common lymphoid malignan-
cy, accounting for 15% of all hematologic malignancies in the
United States.1Quantifying and immunotyping of parapro-
teins has an important role in the diagnosis, classification, and
management of this disorder. In addition, a premalignant
lesion, monoclonal gammopathy of undetermined signifi-
cance (MGUS), is usually diagnosed and followed up by
serum protein electrophoresis. Currently, the method of choice
for detection of serum or urine paraprotein is protein elec-
trophoresis on agarose gel (AGE). Serum proteins are separat-
ed into 6 regions: albumin, α1, α2, β1, β2, and γ. The gel is
stained with amido black or another protein stain, and the con-
centration of each band is quantified by a densitometer.
Paraprotein is usually shown as a sharp peak in the γ region.
Immunotypes are determined by immunofixation elec-
trophoresis (IFE) in which specific antibodies are overlaid
after electrophoresis and the corresponding immunoglobulin
(IgG, IgA, IgM, κ, and λ) is bound and visualized by acid vio-
let or another protein stain.
Capillary zone electrophoresis (CZE) has emerged as a
powerful technique. The technique achieves serum protein
separation into the same 6 regions as AGE but does so with-
out using gels. Rather separation is accomplished in a liquid
buffer system running through parallel, narrow-bored capillar-
ies consisting of fused silica. The narrow-bored capillaries
permit the use of very high voltage. Details of the CZE tech-
nique have been reviewed recently.2,3The sample runs
through the narrow capillary tube, and direct protein detection
is achieved by a measurement at 200 nm, eliminating the need
for staining while improving accuracy and linearity. This
method has the advantages of high efficiency (multiple sam-
ples can be run in parallel), and the system is fully automated.
Am J Clin Pathol 2007;128:293-299 299
© American Society for Clinical Pathology
requires emergency intervention to prevent devastating conse-
quences. Although IgM myeloma is rare (<1%), it may have
some clinical features that overlap with Waldenström
macroglobulinemia.20In addition, up to 20% of myeloma
cases have no detectable heavy chain in the serum. Thus, it is
imperative to correctly determine IgM and free light chain
paraproteins to diagnose the disease and monitor its progres-
sion. In this regard, the performance of the CAPILLARYS 2
CZE/immunosubtraction is less sensitive than IFE, especially
for the detection of low concentrations of paraproteins, which
may signal an early stage of the disease. In fact, a recently pro-
posed diagnostic criterion for Waldenström macroglobuline-
mia includes IgM monoclonal gammopathy of any concentra-
tion, among other features.21
The CAPILLARYS 2 offers increased sample throughput
for serum protein electrophoresis. In our hands, a typical 30-
well AGE takes approximately 1.5 hours, whereas the CZE
offers 90 samples per hour. A 4-sample IFE gel also takes
about 1.5 hours, while CZE/immunosubtraction does 10 sam-
ples per hour. On the other hand, the reagent costs are more
for the CZE/immunosubtraction. Overall, the costs of running
either system are similar in our hands. Serum IgD and IgE,
urine electrophoresis, and cerebrospinal fluid electrophoresis
are not offered on the CZE/immunosubtraction system at this
time. Having both systems provides significant backup capa-
bility for serum protein electrophoresis.
Based on our experience, the performance of CAPIL-
LARYS 2 CZE/immunosubtraction is similar to that of
AGE/IFE in terms of specificity; however, the detection of
monoclonal paraproteins and their immunotyping seems less
sensitive for IgM and, possibly, for free light chains.
From the Department of Pathology, University of Alabama at
Preliminary results of this study were presented at the 41st
annual meeting of the Academy of Clinical Laboratory Physicians
and Scientists; June 2006; Chicago, IL.
Address reprint requests to Dr Hardy: Dept of Pathology,
P230 West Pavilion, University of Alabama at Birmingham, 619 S
19th St, Birmingham, AL 35233.
We gratefully acknowledge the statistical contributions of Dr
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Immunopathology / ORIGINAL ARTICLE