Evaluation of a magnetic particles-based chemiluminescence enzyme immunoassay for Golgi protein 73 in human serum

Background: Golgi protein 73 (GP73) is regarded as a potential serum biomarker for early diagnosis of hepatocellular carcinoma (HCC). We developed a rapid magnetic particles-based chemiluminescence enzyme immunoassay (MPs-CLEIA) for the determination of serum GP73. Methods: Fluorescein isothiocyanate (FITC) and alkaline phosphatase (ALP) were used to label 2 different monoclonal antibodies to GP73. Serum GP73 was captured with labeled antibodies and formed a sandwiched immunoreaction. The magnetic particles (MPs) coated with anti-FITC antibody were used as a means of separation of the GP73 protein from other serum proteins. After adding the enzyme substrate solution, the relative light unit (RLU) was measured. A MPs-CLEIA for serum GP73 was established and evaluated. Results: The RLU was directly proportional to the concentration of GP73. The method linearity was 5-600 mu g/I. Limit of the blank was 2.19 mu g/I. The intra- and inter-assay imprecision was <3% and <5%, respectively. The average recoveries were between 95% and 105%. The proposed method showed a good correlation with a commercial ELISA assay (r = 0.983, p < 0.001). We also evaluated the efficiency of serum GP73 measurement for the diagnosis of HCC using this assay. The area under the receiver operating characteristic curve was 0.822 (95% CI, 0.73-0.89), and the sensitivity and specificity, with cut-off value of 115.6 mu g/I, were 75.4% and 92.1%, respectively. Conclusions: The proposed method demonstrates an acceptable performance for quantifying serum GP73. This assay could be appropriate for routine use in clinical laboratories. (C) 2015 Elsevier B.V. All rights reserved.