Skip to main content

ORIGINAL RESEARCH article

Front. Neurol.
Sec. Neurological Biomarkers
Volume 15 - 2024 | doi: 10.3389/fneur.2024.1504260
This article is part of the Research Topic Autoantibodies and autoimmune neuromuscular disorders View all 3 articles

Applicability of a serodiagnostic line blot for idiopathic inflammatory myopathy: the muscle biopsy is not all

Provisionally accepted
Pedro Nogueira Fontana Pedro Nogueira Fontana 1,2*Vinícius Gomes da Silva Vinícius Gomes da Silva 2Roseli Corazzini Roseli Corazzini 2Natália Merten Athayde Natália Merten Athayde 2Ana Marina Dutra Ferreira da Silva Ana Marina Dutra Ferreira da Silva 2Igor Brockhausen Igor Brockhausen 2Carolina da Cunha Correia Carolina da Cunha Correia 1Cláudia F R Sobreira Cláudia F R Sobreira 3Pedro Tomaselli Pedro Tomaselli 3Flávio Petean Flávio Petean 3Rodrigo de Oliveira Rodrigo de Oliveira 3Pablo Feitoza Pablo Feitoza 4Michel Moraes Soane Michel Moraes Soane 5Natália Saraiva Natália Saraiva 5Rafaela Hidalgo Rafaela Hidalgo 5Cláudia Fideles Cláudia Fideles 5David Feder David Feder 2Alzira Carvalho Alzira Carvalho 2*
  • 1 Universidade de Pernambuco, Recife, Pernambuco, Brazil
  • 2 Centro Universitário ABC, Santo André, Brazil
  • 3 University of São Paulo, Ribeirão Preto, Ribeirão Preto, São Paulo, Brazil
  • 4 Federal University of Amazonas, Manaus, Amazonas, Brazil
  • 5 EUROInstitute - EUROIMMUN Brasil, São Caetano do Sul, Brazil

The final, formatted version of the article will be published soon.

    Abstract Introduction Differential diagnosis of rare idiopathic inflammatory myopathies (IIM) is mainly based on clinical aspects, muscle biopsy analysis, and auxiliary assays that determine myositis-specific and associated autoantibodies (MSA and MAA). While MSAs are considered specific for their respective IIM subclass, MAAs can be present in more than one subclass and in other conditions. This study compares results of a multispecific line blot assay with the final diagnosis of IIM patients based on clinical features and muscle biopsy to draw conclusions for the test’s applicability in the diagnostic workflow. Methods Samples from patients (n=50) diagnosed with various forms of IIM, including patients (n=5) with other myopathies, were analyzed using the EUROLINE Autoimmune Inflammatory Myopathies 16 Ag (IgG), an anti-HMGCR (IgG) line blot, and the Anti-cN-1A ELISA (IgG, all EUROIMMUN). Results MSA and MAA were detected in 74.0% (37/50) of sera and were concordant with the final diagnosis in 64.8% (24/37), discordant in 16.2% (6/37) and not evaluable in 18.9% (7/37) of cases. In 100% (5/5) of patients with other myopathies, no MSA was found. MSA/MAA-co-positivity was observed in 18.0% (9/50) of patients. In 30.0% (15/50) of cases, the muscle biopsy analysis was essential to establish the final diagnosis. Conclusion The agreement between serodiagnostic results and final diagnosis highlights the applicability of the EUROIMMUN myositis-related diagnostic test as first line diagnostic tool in the IIM diagnosis workflow and suggests morphological analysis in cases of inconclusive or negative serology. However, results of diagnostic assays shall always be interpreted in combination with clinical features.

    Keywords: Idiopathic inflammatory myopathies, Myositis-specific antibodies, Muscle biopsy, Dermatomyositis, Immune-mediated necrotizing myopathy, Anti-synthetase syndrome, inclusion body myositis, Myositis-associated antibodies

    Received: 30 Sep 2024; Accepted: 11 Dec 2024.

    Copyright: © 2024 Fontana, da Silva, Corazzini, Athayde, Ferreira da Silva, Brockhausen, Correia, Sobreira, Tomaselli, Petean, de Oliveira, Feitoza, Moraes Soane, Saraiva, Hidalgo, Fideles, Feder and Carvalho. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence:
    Pedro Nogueira Fontana, Universidade de Pernambuco, Recife, 50100-010, Pernambuco, Brazil
    Alzira Carvalho, Centro Universitário ABC, Santo André, Brazil

    Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.