Anti-Cytosolic 5′-Nucleotidase 1A in the Diagnosis of Patients with Suspected Idiopathic Inflammatory Myopathies: An Italian Real-Life, Single-Centre Retrospective Study
Brunetta Porcelli,
Miriana d’Alessandro,
Latika Gupta,
Silvia Grazzini,
Nila Volpi,
Maria Romana Bacarelli,
Federica Ginanneschi,
Giovanni Biasi,
Francesca Bellisai,
Marta Fabbroni,
David Bennett,
Claudia Fabiani,
Luca Cantarini,
Elena Bargagli,
Bruno Frediani,
Edoardo Conticini
Affiliations
Brunetta Porcelli
UOC Laboratorio Patologia Clinica, Policlinico S. Maria alle Scotte, AOU Senese, 53100 Siena, Italy
Miriana d’Alessandro
Respiratory Diseases Unit, Department of Medical and Surgical Sciences & Neurosciences, University of Siena, 53100 Siena, Italy
Latika Gupta
Department of Clinical Immunology and Rheumatology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow 226014, India
Silvia Grazzini
Rheumatology Unit, Department of Medicine, Surgery and Neurosciences, University of Siena, 53100 Siena, Italy
Nila Volpi
Neurology and Clinical Neurophysiology Unit, Department of Medical, Surgical and Neurological Sciences, University of Siena, 53100 Siena, Italy
Maria Romana Bacarelli
UOC Laboratorio Patologia Clinica, Policlinico S. Maria alle Scotte, AOU Senese, 53100 Siena, Italy
Federica Ginanneschi
Neurology and Clinical Neurophysiology Unit, Department of Medical, Surgical and Neurological Sciences, University of Siena, 53100 Siena, Italy
Giovanni Biasi
Rheumatology Unit, Department of Medicine, Surgery and Neurosciences, University of Siena, 53100 Siena, Italy
Francesca Bellisai
Rheumatology Unit, Department of Medicine, Surgery and Neurosciences, University of Siena, 53100 Siena, Italy
Marta Fabbroni
Rheumatology Unit, Department of Medicine, Surgery and Neurosciences, University of Siena, 53100 Siena, Italy
David Bennett
Respiratory Diseases Unit, Department of Medical and Surgical Sciences & Neurosciences, University of Siena, 53100 Siena, Italy
Claudia Fabiani
Ophthalmology Unit, Department of Medicine, Surgery and Neurosciences, University of Siena, 53100 Siena, Italy
Luca Cantarini
Rheumatology Unit, Department of Medicine, Surgery and Neurosciences, University of Siena, 53100 Siena, Italy
Elena Bargagli
Respiratory Diseases Unit, Department of Medical and Surgical Sciences & Neurosciences, University of Siena, 53100 Siena, Italy
Bruno Frediani
Rheumatology Unit, Department of Medicine, Surgery and Neurosciences, University of Siena, 53100 Siena, Italy
Edoardo Conticini
Rheumatology Unit, Department of Medicine, Surgery and Neurosciences, University of Siena, 53100 Siena, Italy
Background: Anti-cytosolic 5′-nucleotidase 1A (anti-cN1A) antibodies were proposed as a biomarker for the diagnosis of inclusion body myositis (IBM), but conflicting specificity and sensitivity evidence limits its use. Our study aimed to assess the diagnostic accuracy of anti-cN1A in a cohort of patients who underwent a myositis line immunoassay for suspected idiopathic inflammatory myopathies (IIM). We also assessed the agreement between two testing procedures: line immunoassay (LIA) and enzyme-linked immunoassay (ELISA). Materials and methods: We collected retrospective clinical and serological data for 340 patients who underwent a myositis antibody assay using LIA (EUROLINE Autoimmune Inflammatory Myopathies 16 Ag et cN-1A (IgG) line immunoassay) and verification with an anti-cN1A antibody assay using ELISA (IgG) (Euroimmun Lubeck, Germany). Results: The serum samples of 20 (5.88%) patients (15 females, 5 males, mean age 58.76 ± 18.31) tested positive for anti-cN1A using LIA, but only two out of twenty were diagnosed with IBM. Seventeen out of twenty tested positive for anti-cN1A using ELISA (median IQR, 2.9 (1.9–4.18)). Conclusions: Our study suggests excellent concordance between LIA and ELISA for detecting anti-cN1A antibodies. LIA may be a rapid and useful adjunct, and it could even replace ELISA for cN1A assay. However, the high prevalence of diseases other than IBM in our cohort of anti-cN1A-positive patients did not allow us to consider anti-cN1A antibodies as a specific biomarker for IBM.
