New chemiluminescent enzyme immunoassay for quantitative measurement of Mac-2 binding protein glycosylation isomer in chronic liver disease.

Background: This study aimed to evaluate the quantitative measurement of Mac-2 binding protein glycosylation isomer (M2BPGi) levels using the new chemiluminescent enzyme immunoassay.

Methods: The data of a total of 347 patients with hepatitis C virus (HCV) infection and 150 health volunteers from 13 locations in Japan were evaluated. The quantitative system for measuring M2BPGi-Qt levels was based on a new chemiluminescent enzyme immunoassay. We evaluated the reproducibility and quantitation range in quantitative M2BPGi-Qt measurement. We also investigated the confidence ratio of M2BPGi-Qt levels measured by the new quantitative system to M2BPGi levels measured by the current semi-quantitative system for validating the clinical utility of the new method.

Results: The reproducibility of M2BPGi-Qt in HCV samples with negative, positive 1+, and positive 2+ was 0.77 ± 0.02 AU/mL, 2.25 ± 0.03 AU/mL, and 6.55 ± 0.21 AU/mL, respectively, and the corresponding coefficient of variation (CV)s were 2.1%, 1.3%, and 3.2%, respectively. The range of quantification assessment resulted that all CVs showed less than 5% in investigated range. Sample stability testing found that the mean percentage difference between the pre- and post-storage values of 6 samples ranged between 96.2 and 103.9%. The correlation coefficient between M2BPGi and M2BPGi-Qt in patients with HCV and the healthy volunteers was 0.986 and 0.991, respectively. M2BPGi-Qt could be quantitatively assessed in a patient with over 20 C.O.I.

Conclusion: Compared with qualitative methods, the M2BPGi quantitative measurement system could provide a numerical value unaffected by interpretation bias, and measurements are more precise at high M2BPGi levels.