Autoantibodies to Mi-2 alpha and Mi-2 beta in patients with idiopathic inflammatory myopathy.

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.

• Authors: Michaelin Richards, Ignacio García-De La Torre, Yelitza C González-Bello, Mónica Vázquez-Del Mercado, Lilia Andrade-Ortega, Gabriel Medrano-Ramírez, Jose Eduardo Navarro-Zarza, Marco Maradiaga-Ceceña, Esthela Loyo, Armando Rojo-Mejía, Graciela Gómez, Andrea Seaman, Marvin J Fritzler, Martial Koenig, Michael Mahler
• Journal: Rheumatology (Oxford, England) (Rheumatology (Oxford)) Vol. 58 Issue 9 Pg. 1655-1661 (09 01 2019) ISSN: 1462-0332 [Electronic] England
• PMID: 30938432 (Publication Type: Journal Article, Review)
• Copyright: © The Author(s) 2019. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For permissions, please email: [email protected].

Chemical References

• Autoantibodies
• Biomarkers
• CHD4 protein, human
• Mi-2 antibodies
• Mi-2 Nucleosome Remodeling and Deacetylase Complex

Topics

• Autoantibodies (blood)
• Biomarkers (blood)
• Case-Control Studies
• Dermatomyositis (diagnosis, immunology)
• Female
• Humans
• Immunoassay (methods)
• Male
• Mi-2 Nucleosome Remodeling and Deacetylase Complex (immunology)
• Myositis (diagnosis, immunology)
• Polymyositis (diagnosis, immunology)
• ROC Curve
• Reproducibility of Results