Performance Evaluation of a New Enzyme Immunoassay Method for Quantitative Determination of (1→3)-β-D-glucan in the Serum

Abstract

Measurement of (1 → 3)- β -D-glucan (BDG), a component of the fungal cell wall, in the serum is a useful method for the diagnosis of deep-seated mycoses. Although, two kinetic turbidimetric methods based on the clotting activity of Limulus hemocytes and a synthetic chromogenic substrate have been used previously for the measurement, neither method addresses the issue of natural resource conservation. Therefore, the analytical performance of the newly developed Immunotesta BDG reagent (SEKISUI MEDLICAL CO., LTD.), a sandwich enzyme-linked immunosorbent assay (ELISA) using a BDG-specific mon-oclonal antibody, was evaluated in this study. The ELISA good performances regard to accuracy, within-run precision, limit of detection, dilution linearity, and intermediate precision ; in they useful in interference studies. The measurments obtained from the Wako β -glucan Test (turbidimetric assay) and the Fungitec G-test ES “Nissui” (chromogenic assay) were compared with those from the ELISA. The correlation between the results of ELISA and the turbidimetric assay was R = 0.938 (p ＜ 0.001, y = 2.48x +10.6), and that between ELISA and the chromogenic assay was R = 0.971 (p ＜ 0.001, y = 0.97 × ­2.97). The slope of the correlation between the results of the ELISA and the turbidimetric assay was 2.48, and the BDG measurment value differed by about 2 times. A good correlation was observed between the results of the ELISA and the chromogenic assay, and the overall concordance rate of 90.7% was below the cutoff value of 20 pg/mL. These results indicate that the new ELISA method may be useful for obtaining measurements of BDG in the clinical setting.