Michaelin Richards1, Ignacio García-De La Torre2, Yelitza C González-Bello3, Mónica Vázquez-Del Mercado4, Lilia Andrade-Ortega5, Gabriel Medrano-Ramírez6, Jose Eduardo Navarro-Zarza7, Marco Maradiaga-Ceceña8, Esthela Loyo9, Armando Rojo-Mejía10, Graciela Gómez11, Andrea Seaman1, Marvin J Fritzler12, Martial Koenig13, Michael Mahler1. 1. Research and Development, Inova Diagnostics, San Diego, CA, USA. 2. Departamento de Inmunología y Reumatología, Hospital General de Occidente and University of Guadalajara, Guadalajara, Jalisco. 3. Departamento de Reumatología Centro de Estudios, de Investigación Básica y Clínica, S.C., Guadalajara, Jalisco. 4. Servicio de Reumatología, Hospital Civil de Guadalajara 'Dr Juan I. Menchaca', Guadalajara, Jalisco. 5. Departamento de Reumatología Centro Médico Nacional 20 de Noviembre, ISSSTE. 6. Departamento de Reumatología Hospital General de México, 'Dr Eduardo Liceaga', México City. 7. Departamento de Reumatología Hospital General, 'Dr Raymundo Abarca Alarcón', Chilpancingo, Guerrero. 8. Departamento de Reumatología Hospital General de Culiacán, 'Dr Bernardo Gastelum', S.S., Culiacán, Sinaloa, Mexico. 9. Servicio de Reumatología e Inmunología, Clínica Hospital Regional Universitario 'José Ma. Cabral y Báez', Santiago, Rep. Dominicana. 10. Departamento de Reumatología, Clínica San Pablo, Surco, Lima, Perú. 11. Departamento de Inmunología, Instituto de Invest. Médicas, Alfredo Lanari, Universidad de Buenos Aires, Argentina. 12. Department of Medicine, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada. 13. Department of Medicine, Université de Montréal, Montreal, QC, Canada.
Abstract
OBJECTIVES: The objective of this study was to compare the results obtained from different assays for the detection of anti-Mi-2 antibodies, which are important markers in the diagnosis of DM. METHODS: The study included 82 patients (68 females/14 males), most of whom had DM (n = 57), followed by PM (n = 16) and juvenile DM (n = 9). All samples were tested using a novel particle-based multi-analyte technology (PMAT) (Inova Diagnostics, research use only) in parallel with a line immunoassay (LIA: Euroimmun). To assess clinical specificity for the PMAT assay, a total of 775 disease and healthy controls were tested. RESULTS: 29 samples were positive by at least one test for anti-Mi-2 antibodies. Of those, 24 were Mi-2β LIA+, five were Mi-2α LIA+ and 23 Mi-2 PMAT+. The comparison shows varying agreement between the different methods (kappa 0.27-0.77). When LIA results were used as reference for receiver operating characteristics analysis, high area under the curve values were found for both PMAT vs LIA Mi-2α and LIA Mi-2β. When analysing the results in the context of the myositis phenotype, PMAT associated closest with the DM phenotype. In the control group, 3/775 controls (all low levels) were anti-Mi-2+ resulting in a sensitivity and specificity of 28.1% and 99.6%, respectively. CONCLUSION: Overall, good agreement was found between LIA and PMAT for anti-Mi-2 antibodies, which is important for the standardization of autoantibodies. Anti-Mi-2β antibodies measured by PMAT tend be more highly associated with the clinical phenotype of DM.
OBJECTIVES: The objective of this study was to compare the results obtained from different assays for the detection of anti-Mi-2 antibodies, which are important markers in the diagnosis of DM. METHODS: The study included 82 patients (68 females/14 males), most of whom had DM (n = 57), followed by PM (n = 16) and juvenile DM (n = 9). All samples were tested using a novel particle-based multi-analyte technology (PMAT) (Inova Diagnostics, research use only) in parallel with a line immunoassay (LIA: Euroimmun). To assess clinical specificity for the PMAT assay, a total of 775 disease and healthy controls were tested. RESULTS: 29 samples were positive by at least one test for anti-Mi-2 antibodies. Of those, 24 were Mi-2β LIA+, five were Mi-2α LIA+ and 23 Mi-2 PMAT+. The comparison shows varying agreement between the different methods (kappa 0.27-0.77). When LIA results were used as reference for receiver operating characteristics analysis, high area under the curve values were found for both PMAT vs LIA Mi-2α and LIA Mi-2β. When analysing the results in the context of the myositis phenotype, PMAT associated closest with the DM phenotype. In the control group, 3/775 controls (all low levels) were anti-Mi-2+ resulting in a sensitivity and specificity of 28.1% and 99.6%, respectively. CONCLUSION: Overall, good agreement was found between LIA and PMAT for anti-Mi-2 antibodies, which is important for the standardization of autoantibodies. Anti-Mi-2β antibodies measured by PMAT tend be more highly associated with the clinical phenotype of DM.
Authors: Michael Mahler; Kishore Malyavantham; Andrea Seaman; Chelsea Bentow; Ariadna Anunciacion-Llunell; María Teresa Sanz-Martínez; Laura Viñas-Gimenez; Albert Selva-O'Callaghan Journal: Diagnostics (Basel) Date: 2021-11-30