Determination of β_2-Microglobulin in Biological Samples Using an Immunoenzymometric Assay (Chemiluminescence Detection) or an Immunoturbidimetric Assay: Comparison with a Radioimmunoassay

摘要

Monitoring β_2-microglobulin (β2M) in biological fluids has gained considerable interest in pathologies such as haematologic malignancies, renal diseases, and chronic inflammatory diseases. Due to limitations of the RIA in the routine laboratory, we measure β2M with non-isotopic methods. 189 patients suffering from myeloma (n=66), end stage renal failure (n=54) or inflammation (n=69) were included in this study. β2M was determined in serum, urine and dialysate using an immunoenzymometric assay with Chemiluminescence detection [Immulite Diagnostic Products Corporation (DPC), La Garenne Colombes, France] and an immunoturbidimetric assay (Olympus, Rungis, France). The data were compared with a radioimmunoassay (Immunotech, Marseille, France) taken as a reference. Using serum samples, the immunoenzymometric assay with Chemiluminescence detection and the immunoturbidimetric assay have reliable analytical performances. Values obtained with serum samples are highly correlated with the radioimmunoassay (DPC/RIA r~2=0.84; Olympus/RIA r~2=0.94) whatever the type of pathology; however an over-estimation which could be related to cross reactivity with β2M fragments was observed with the RIA method as suggested by crossover calibration and recovery studies. Values obtained with urinary samples (n=96) are closely related to those obtained with the RIA (DPC/RIA r~2 = 0.98; Olympus/RIA: r~2=0.99). Despite the low levels observed in dialysate (n=S7) good correlations were observed between Olympus vs DPC (r~2=0.85). By contrast, the two non-isotope methods are poorly related with the RIA method (DPC vs RIA r2=0.47 and Olympus vs RIA r~2=0.54). In conclusion, the immunoenzymometric assay with Chemiluminescence detection or the immunoturbidimetric assay could be used in the routine laboratory in order to determine β2M in plasma, urine and dialysate.