Epitope characterization of an anti-PIVKA-II antibody and evaluation of a fully automated chemiluminescent immunoassay for PIVKA-II

AbstractObjectivesProtein induced by vitamin K absence or antagonist-II (PIVKA-II) has been used as a tumor marker to aid in the diagnosis of hepatocellular carcinoma (HCC). We developed an anti-PIVKA-II monoclonal antibody, 3C10, and a fully automated quantitative immunoassay for PIVKA-II on the ARCHITECT® i-systems. The aim of this study was to characterize the epitope of 3C10 and to evaluate the reactivity to PIVKA-II of this assay.MethodsThe epitope characterization was examined by using prothrombin γ-carboxyglutamic acid residues (Gla) domain polypeptides which are amino acid residues 17–27 that include four Gla residues at positions 19, 20, 25 and 26. The correlation with Picolumi PIVKA-II MONO (Eidia, Tokyo, Japan) and tube type equivalency was evaluated by using the developed fully automated quantitative immunoassay.ResultsPeptides having glutamic acid residues (Glu) at Gla domains strongly reacted to 3C10 but lost reactivity when the Glu at positions 19 or 20 was changed to Gla. The results were equivalent with an existing in vitro diagnostics product for PIVKA-II using the MU-3 antibody. A correlation study with the Picolumi PIVKA-II MONO gave a correlation coefficient of 0.99 and a regression slope of 0.92. No difference between a plain serum tube and a rapid serum tube including thrombin (RST) was observed on ARCHITECT PIVKA-II.ConclusionsThe results demonstrate that this anti-PIVKA-II antibody detects equivalent epitopes with MU-3 and has equivalent reactivity to PIVKA-II as MU-3. Moreover, the ARCHITECT PIVKA-II assay has good correlation with the existing PIVKA-II product, and is applicable for use with RST

異常プロトロンビン（PIVKA-II）のイムノアッセイの開発および特性解析

筑波大学 (University of Tsukuba)201

異常プロトロンビン（PIVKA-II）のイムノアッセイの開発および特性解析

筑波大学 (University of Tsukuba)201

Development and analytical performance evaluation of an automated chemiluminescent immunoassay for pro-gastrin releasing peptide (ProGRP)

Background: Pro-gastrin releasing peptide ( ProGRP) concentrations in blood play an important role in the diagnosis and treatment of patients with small cell lung cancer (SCLC). The automated quantitative ARCHITECT (R) ProGRP assay was developed to aid in the differential diagnosis and in the management of SCLC. The purpose of this study was to evaluate the analytical performance of this chemiluminescent microparticle immunoassay at multiple sites. Methods: ARCHITECT ProGRP measures ProGRP using a two-step sandwich using monoclonal anti-ProGRP antibodies coated on paramagnetic microparticles and labeled with acridinium. Analytical performance of the assay was evaluated at four sites: Abbott Japan, Denka Seiken, the Johns Hopkins University, and the University of Munich. Results: Total precision (%CV) for nine analyte concentrations was between 2.2 and 5.7. The analytical sensitivity of the assay was between 0.20 pg/mL and 0.88 pg/mL. The functional sensitivity at 20% CV was between 0.66 pg/mL and 1.73 pg/mL. The assay was linear up to 50,000 pg/mL using a 1:10 autodilution protocol. The calibration curve was stable for 30 days. Comparison with the Fujirebio microtiter plate enzyme-linked immunosorbent assay (EIA) ProGRP assay gave a slope of 0.93 and a correlation coefficient (r) of 0.99. Conclusions: These results demonstrate that the ARCHITECT ProGRP assay has excellent sensitivity, precision, and correlation to a reference method. This assay provides a convenient automated method for ProGRP measurement in serum and plasma in hospitals and clinical laboratories. Clin Chem Lab Med 2009;47:1557-63