Evaluación de la electroforesis capilar como método de detección y medida de proteína de Bence Jones

Resumo

Introduction: Bence-Jones proteins (BJP) are monoclonal immunoglobulin free light chains that are detected in urine due to an over-production by a B-lymphocyte clone. BJP have been linked to various diseases, with significant clinical signance. In this work, capillary electrophoresis (CE) has been evaluated as a technique for the detection and quantification of BJP. Material and methods: Twenty four-hour urine samples from 74 patients were analyzed for BJP by CE (with a previous ultrafiltration step), immunofixation, and high resolution electrophoresis on agarose gel. Imprecision and the detection limit of CE were also studied. Results: Sensitivity and specificity of CE was 97.8% and 75.9%, respectively. No differences were found between samples with a high or low urinary total protein concentration. Sensitivity and specificity of agarose were 64.4% and 96.6%, respectively, but these values were higher in samples with a urinary total protein concentration above 150 mg/L. Imprecision of CE in the quantification of BJP was 1.1-4.5%. Detection limit for kappa and lambda BJP were 3 mg/L and 1 mg/L, respectively. Conclusions: In the detection of BJP by CE, sensitivity, specificity and reproducibility were very high, whereas the detection limit was very low. CE requires the prior treatment of samples, but it provides an automated and reproducible method for detecting and measuring BJP, with a sensitivity very close to that of immunofixation.