A Comparison of gel (Hydragel 30) and capillary (Capillarys III Tera) electrophoresis for the characterization of human serum proteins

OBJECTIVES: To compare gel (Hydrasys 2 from Sebia) and capillary (Capillarys III Tera, Sebia) electrophoresis for the characterization of human serum proteins. DESIGN AND METHODS: 304 sera tested by gel electrophoresis during 8 routine laboratory days were concurrently tested by capillary electrophoresis. Gels were read by an experienced medical technologist while capillary profiles by a Sebia representative and the same technologist. Most sera (214 of 304, 70%) were also analyzed by immunofixation electrophoresis, used here as the gold standard to calculate sensitivity and specificity of the gel and capillary systems. RESULTS: Gel and capillary estimated the concentration of albumin, gamma region, and M-spikes nearly perfectly, and that of beta, alpha-2, and alpha-1 regions with excellent correlation. The two systems classified concordantly 268 of 304 sera (88% agreement) as having no, one, or two M-spikes, but differed in the remaining 36 sera (12%). Gel electrophoresis correctly identified M-spikes in 82 of 112 sera that were shown to have monoclonal band(s) by immunofixation (73% sensitivity), and correctly did not reveal M-spikes in 97 of the 102 sera that had no immunofixation bands (95% specificity). Capillary achieved slightly higher sensitivity (85 of 112, 76%) and slightly lower specificity (94 of 102, 92%), but the two areas under the ROC curves were nearly identical at 0.84. CONCLUSIONS: Gel and capillary electrophoresis systems perform similarly to estimate the concentration of serum protein fractions and detect M-spikes.