Detection and identification of low-concentration M proteins with CZE/IS; a 'dry' analysis.
The accuracy of detection and identification of low-concentration M proteins using capillary zone electrophoresis/immunosubtraction (CZE/IS) plots was systematically studied. To this end, 49 CZE plots (protein spectra; session I) and CZE/IS plots (spectra with corresponding immunosubtraction plots; session II) were judged by participants from 12 Dutch laboratories. Plots were based on mixed sera with a low concentration (0.4, 1 or 4 g/L) of one M protein, as well as normal sera, sera with an oligoclonal or polyclonal increase in immunoglobulins, and sera containing free monoclonal light chains. At 0.4 g/L, nine out of 12 (9/12) different M proteins were hard to detect. At 1 g/L, 6/12 M proteins were detected by > 85% of the participants. At 4 g/L, 10/12 M proteins were detected by all participants. Normal spectra were always judged correctly. At 1 g/L and 4 g/L, detected M proteins were identified correctly by 92% of the participants, versus only 63% at 0.4 g/L. The detection accuracy was only slightly (non-significantly) improved by the application of IS plots. Our data indicate that CZE/IS is applicable for most M proteins at concentrations > or = 4 g/L.
Keularts
Irene M L W
IM
Department of Clinical Chemistry and Haematology, St. Franciscus Gasthuis, P. O. Box 10900, 3004 BA Rotterdam, Netherlands. i.keularts@sfg.nl
Beunis
Marlene H
MH
van Oord
John
J
Janssen
Johannes W
JW
D000911:Antibodies, Monoclonal / Q000097:blood*; D019075:Electrophoresis, Capillary / Q000379:methods*; D006801:Humans; D007147:Immunoglobulin Light Chains / Q000097:blood*; D007158:Immunologic Techniques
D000911:Antibodies, Monoclonal; D007147:Immunoglobulin Light Chains