Abstract Number: PB0671
Meeting: ISTH 2020 Congress
Background: Protein S (PS) is a vitamin K-dependent glycoprotein present in plasma under free active form (FPS) or complexed to C4b-binding protein, which availability regulates the proportion of the different PS forms. Congenital or acquired PS deficiencies are a risk factor for venous thrombosis. PS levels are influenced by age, sex, oral contraceptive use, anti-vitamin K therapy and PS gene polymorphism. PS levels may decrease in various contexts such as pregnancy, hepatic disorders, early stages of inflammatory diseases. PS deficiency is diagnosed using PS antigen assay and functional PS activity assay. A new, fully automated, immunoturbidimetric assay for FPS is developed for use on any coagulation analyzer.
Aims: To report diagnostic performance characteristics of this new FPS latex immunoassay on CS-2500.
Methods: LIAPHEN Free Protein S is an immunoturbidimetric method, based on antigen-antibody reaction: FPS antigen of the sample reacts with Latex particles sensitized with two mouse monoclonal anti-FPS antibodies, leading to latex particles agglutination. Performances are evaluated using the commercial lyophilized plasma calibrator and controls on CS-2500, and comparison studies with other commercially available assays are performed using 89 plasma samples from healthy subjects (n= 41) or PS-deficient individuals with various pathologies (n= 48).
Results: Between-run precision coefficients of variation (CV%, n=20), evaluated using lyophilized plasmas with normal and pathological FPS levels are 1.6% and 1.9% respectively. The LIAPHEN Free PS antigen measurement on patients’ plasmas is well correlated with STA Staclot Protein S functional assay (n=54, r=0.916, p< 0.0001). An excellent correlation is obtained in comparison with STA-Liatest Free Protein S on STA-R: y=0.96x-1.35, r=0.953, p< 0.0001.
Conclusions: This new FPS assay is highly sensitive, specific, reproducible and standardized to rapidly assess Free PS concentrations in human citrated plasma. It is a useful tool for the diagnosis of PS deficiencies.
To cite this abstract in AMA style:Dunois C, Gueret P, Parage R, Pontis A, Nedelec F, Gouin I, Amiral J. Diagnostic Performances Evaluation of LIAPHEN Free Protein S on CS-2500 [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/diagnostic-performances-evaluation-of-liaphen-free-protein-s-on-cs-2500/. Accessed October 2, 2023.
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