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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.

The diagnosis of drug allergy is mainly based upon a detailed clinical history, positive skin tests (ST) and detection of specific IgE. In case of discrepant results, in vitro investigations to identify the responsible drug are needed. The histamine release test (HR) is usually performed. Nevertheless, its clinical benefit remains controversial. Flow cytometric methods (FCM) for the study of allergen induced basophil activation have been recently described. We assessed their usefulness in the diagnosis of drug allergy in comparison to HR results. Eighteen patients were included and 24 drugs (mainly antibiotics and muscle relaxant drugs) were tested. On the basis of clinical signs, 15 patients were classified as allergic (18 drugs). Sensitivity of biological investigations were found as follows: 71% (ST), 71% (FCM) and 24% (HR). This suggests performing FCM rather than HR. In addition, HR is more costly in terms of both reagents and laboratory technician time. Thus, CD63 detection by FCM seems to be a more reliable method in the clinical immunology laboratory. Additional data are needed to validate these preliminary results (sensitivity and specificity, especially in atopic patients) and to assess the interest of the method to investigate drug allergy due to other types of molecules.

The variation of Apo SAA has been studied in parallel with HDL disturbances in septic patients to try to define the role of SAA in these lipoproteins abnormalities. 14 septic patients hospitalized in a surgical intensive care unit have been studied. In these patients, the determination of cholesterol, HDL-cholesterol, Apo AI, Apo B, Apo SAA and CRP and lipoprotein electrophoresis have been made between the 4th and the 7th day after admission in the unit. A control group includes 10 patients undergoing an elective knee surgery. Our results show that SAA elevation (480 +/- 250 mg/l) are much greater than CRP ones (137 +/- 38 mg/l) with no correlation between the 2 proteins specially in patients with hepatic failure. As reported by others, we find a diminution of total cholesterol (3.0 +/- 1.2 mmol in our series) and HDL-cholesterol (0.39 +/- 0.18 mmol). Apo AI is dramatically decreased (0.50 +/- 0.29 g/l) such as a negative acute phase protein. The polyacrylamide gel electrophoresis of lipoproteins confirms the HDL decrease and reveals an abnormal migration of this class of lipoprotein in 8 cases/14 cases (4 accelerations and 4 double-bands). From the results, this HDL modification does not seem to correlate with SAA elevation; immunoblotting experiments lead to the same conclusion. The data are discussed and compared to other findings of the literature.