Search

This work aims to define the interest and the limits of free light chain (FLC) determination in serum and urine for the investigation of monoclonal gammopathies. Based on the study of nine typical cases extracted from laboratory practice, the authors demonstrate the interest of this determination for the diagnosis and the monitoring of FLC and non secretory myelomas. This test is also useful for the evaluation of response to chemotherapy and the early detection of relapses in intact immunoglobulin multiple myelomas. These results are discussed in the light of the literature with a special emphasis on AL amyloidosis and monoclonal gammapathy of undetermined significance (MGUS). Finally the authors underline some limitations leading to an overestimation of the results in certain patients together with the difficulty to interpret data when a renal damage is associated.

Capillary electrophoresis represents a relatively new analytical technique. This methodology has diversified and given rise to various modes such as capillary zone electrophoresis, capillary gel electrophoresis, micellar electrokinetic capillary chromatography, capillary isoelectric focusing and capillary isotachophoresis. If capillary electrophoresis was first introduced in research laboratories, this technique is now making an entrance to the clinical laboratory. This is due to its rapid and high-efficiency separation power, its potential applications and its possible automation. Thus, capillary electrophoresis represents an attractive alternative to some time-consuming techniques. Thanks to its versatility, the use of capillary electrophoresis has been proposed for the separation and quantification of a wide spectrum of biological components ranging from macromolecules (proteins, lipoproteins, nucleic acids) to small analytes (amino acids, organic acids or drugs). This paper illustrates the potential of capillary electrophoresis which should rapidly become a major technology for a modern clinical laboratory.

Serum protein electrophoresis and typing of monoclonal components (MCs) are routine but time-consuming and technically demanding assays. We evaluated capillary electrophoresis (Paragon CZE 2000) for automation of the two assays. CZE and cellulose acetate electrophoresis gave similar data on 794 samples. Within-run and between-run CVs were2% for albumin and gamma-globulins and 4-7% for alpha 1-, alpha 2-, and beta-globulins. Bilirubin, hemoglobin, triglycerides, and fibrinogen were found not to interfere. No carryover by capillaries was detected. The detection limit for MC was0.5 g/L. MC assessment by immunosubtraction on 403 samples identified the monoclonal type in all samples with peak concentrations10 g/L; only 50% of MCs that could not be quantified by densitometric scan were typed.

We assessed the combined use of serum protein electrophoresis (SPE) and nephelometric measurement of immunoglobulin heavy- and light-chain components for detecting serum monoclonal immunoglobulins (monoclonal components, MC) in 4788 unselected samples from 4173 patients. MC were detected in 514 samples from 390 patients. In 356 these were detected by SPE; the other 34 had a normal SPE pattern but an abnormal kappa:lambda light-chain ratio (KLR). Only 208 of the 356 (58%) samples with bands by SPE had abnormal KLRs. Samples with MC concentrations greater than 5 g/L had a higher proportion of abnormal KLRs (75%) than those with concentrations less than 5 g/L (42%). The KLR was abnormal in 13% of samples in which no MC were visible by SPE or immunofixation electrophoresis (IFE). Compared with quantitative measurements of immunoglobulin heavy and light chains, high-quality SPE remains the method of choice for the detection of MC. Quantitative methods, however, are able to detect additional MC, especially those containing free light chains, and in the absence of SPE and IFE will detect about 75% of MC present at greater than 5 g/L.