title: Heterogeneous clinical spectrum of anti-SRP myositis and importance of the methods of detection of anti-SRP autoantibodies: a multicentric study.
abstract: Anti-signal recognition particle (SRP) antibodies are important serological markers for the diagnosis and the prognosis of idiopathic inflammatory myopathy (IIM), especially to distinguish immune-mediated necrotizing myopathy (IMNM). This study was set up to investigate the phenotype associated with anti-SRP antibodies and to evaluate the methods for detecting these antibodies. Clinical and biological data were retrospectively obtained from 60 adult patients with anti-SRP antibodies detected by a dot immunoassay from 12 centers. Thirty-six (60 %) out of these 60 patients suffered from an IIM, and among them, 21 patients were diagnosed as IMNM. Among patients with a definite IIM, proximal weakness and myalgia were prominent symptoms at the time of diagnosis. Only few patients displayed severe extra-muscular symptoms such as cardiac involvement or severe myositis. Mean creatine kinase levels were high for all patients except for two of them. When testing by indirect immunofluorescence (IIF) on HEp2 cells, the fraction of patients displaying the typical anti-SRP fine speckled staining of the cytoplasm was higher in patients with IIM (30/36) (83 %) than in patients with non-IIM (3/24) (12.5 %) (p < 0.0001). Thirty (91 %) out of 33 patients with a positive immunodot and a characteristic IIF cytoplasmic staining suffered from a clinical definite myositis, whereas only 6 (22 %) out of 27 patients with a positive immunodot but a negative cytoplasmic pattern suffered from a myositis (p < 0.00001). This series highlights the strong heterogeneity of anti-SRP positivity that encompassed IMNM and non-IMNM and supports the necessity of considering both IIF and dot immunoassay to confirm the diagnosis of anti-SRP-associated myositis.
authors.affiliation: Department of Immunology, Centre Hospitalier Lyon-Sud, Hospices Civils de Lyon, chemin du grand revoyet, 69495, Pierre-Benite Cedex, France.
authors.forename: Cécile
authors.initials: C
authors.lastname: Picard
authors.affiliation: Groupe d'Etude de l'Auto-Immunité (GEAI), 49933, Angers, France.|Department of Immunology, St Eloi Hospital, Montpellier University, CHRU de Montpellier, 34295, Montpellier Cedex 5, France.
authors.forename: Thierry
authors.initials: T
authors.lastname: Vincent
authors.affiliation: Department of Internal and Vascular Medicine, Centre Hospitalier Lyon-Sud, Hospices Civils de Lyon, Université Lyon-1, 69495, Pierre-Benite Cedex, France.
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Lega
authors.affiliation: Groupe d'Etude de l'Auto-Immunité (GEAI), 49933, Angers, France.|Department of Immunology, CHU Henri Mondor - Service d'Immunologie Biologique, 94010, Créteil, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Hue
authors.affiliation: Groupe d'Etude de l'Auto-Immunité (GEAI), 49933, Angers, France.|Department of Immunology, Hôpital Rangueil, 31059, Toulouse, Cedex 9, France.
authors.forename: Françoise
authors.initials: F
authors.lastname: Fortenfant
authors.affiliation: Groupe d'Etude de l'Auto-Immunité (GEAI), 49933, Angers, France.|Department of Immunology, CHU Dijon, 21079, Dijon, Cedex, France.
authors.forename: Daniela
authors.initials: D
authors.lastname: Lakomy
authors.affiliation: Groupe d'Etude de l'Auto-Immunité (GEAI), 49933, Angers, France.|Laboratoire Luxembourgeois d'Immuno-Pathologie, 4149, Esch-Suralzette, Luxembourg.
authors.forename: René-Louis
authors.initials: RL
authors.lastname: Humbel
authors.affiliation: Groupe d'Etude de l'Auto-Immunité (GEAI), 49933, Angers, France.|Department of Immunology, Nouvel Hôpital Civil, 67091, Strasbourg, France.
authors.forename: Joelle
authors.initials: J
authors.lastname: Goetz
authors.affiliation: Department of Medical Information, CHU de Montpellier, UMR Mistea, 34295, Montpellier, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Molinari
authors.affiliation: Groupe d'Etude de l'Auto-Immunité (GEAI), 49933, Angers, France.|Department of Biological Immunology, UMR-S 1076, Faculté de Pharmacie, LBM AP-HM et Aix-Marseille-Université, 13005, Marseille, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Bardin
authors.affiliation: Department of Biological Immunology, UMR CNRS/AMU 7259, LBM AP-HM et Aix-Marseille-Université, 13005, Marseille, France.
authors.forename: Daniel
authors.initials: D
authors.lastname: Bertin
authors.affiliation: Groupe d'Etude de l'Auto-Immunité (GEAI), 49933, Angers, France.|Department of Immunology, AP-HP hôpital Saint-Antoine, UFR 967, Faculté de medecine, Université Pierre et Marie Curie, 75571, Paris Cedex 12, France.
authors.forename: Catherine
authors.initials: C
authors.lastname: Johanet
authors.affiliation: Groupe d'Etude de l'Auto-Immunité (GEAI), 49933, Angers, France.|Department of Immunology, CHU Bicetre, 94270, Kremlin Bicêtre, France.
authors.forename: Pascale
authors.initials: P
authors.lastname: Chretien
authors.affiliation: Groupe d'Etude de l'Auto-Immunité (GEAI), 49933, Angers, France.|Department of Immunology, Univ Lille Nord de France, 59000, Lille, France.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Dubucquoi
authors.affiliation: Hôpital Cardiovasculaire et pneumologique, Hospices Civils de Lyon, 69677, Bron, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Streichenberger
authors.affiliation: Groupe d'Etude de l'Auto-Immunité (GEAI), 49933, Angers, France.|Department of Biological Immunology, UMR CNRS/AMU 7259, LBM AP-HM et Aix-Marseille-Université, 13005, Marseille, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Desplat-Jégo
authors.affiliation: Groupe d'Etude de l'Auto-Immunité (GEAI), 49933, Angers, France.|Department of Microbiology and Immunology, Catholic University of Leuven, Louvain, Belgium.|Department of Laboratory Medicine, University Hospitals Leuven, Louvain, Belgium.
authors.forename: Xavier
authors.initials: X
authors.lastname: Bossuyt
authors.affiliation: Groupe d'Etude de l'Auto-Immunité (GEAI), 49933, Angers, France.|Department of Rheumatology, Centre national de référence des maladies auto-immunes systémiques rares, CHU Hautepierre, Université de Strasbourg, 67098, Strasbourg, France.
authors.forename: Jean
authors.initials: J
authors.lastname: Sibilia
authors.affiliation: Groupe d'Etude de l'Auto-Immunité (GEAI), 49933, Angers, France.|Departamento Universitário de Imunologia, Universidade Nova de Lisboa - Faculdade de Ciências Médicas, 1169-056, Lisbon, Portugal.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Abreu
authors.affiliation: Groupe d'Etude de l'Auto-Immunité (GEAI), 49933, Angers, France.|Department of Immunology and Allergology, CHU Hôpital Larrey, Institut de Biologie en Santé, 49933, Angers Cedex 9, France.
authors.forename: Alain
authors.initials: A
authors.lastname: Chevailler
authors.affiliation: Department of Immunology, Centre Hospitalier Lyon-Sud, Hospices Civils de Lyon, chemin du grand revoyet, 69495, Pierre-Benite Cedex, France. nicole.fabien@chu-lyon.fr.|Groupe d'Etude de l'Auto-Immunité (GEAI), 49933, Angers, France. nicole.fabien@chu-lyon.fr.
authors.forename: Nicole
authors.initials: N
authors.lastname: Fabien
mesh_terms: D000328:Adult; D000368:Aged; D001323:Autoantibodies / Q000378:metabolism*; D045744:Cell Line, Tumor; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D015151:Immunoblotting; D008297:Male; D008875:Middle Aged; D063806:Myalgia; D009220:Myositis / Q000175:diagnosis* / Q000276:immunology; D009336:Necrosis; D012189:Retrospective Studies; D018271:Signal Recognition Particle / Q000276:immunology
chemical_list: D001323:Autoantibodies; D018271:Signal Recognition Particle
keywords: Anti-SRP antibodies; Immune-mediated necrotizing myopathy; Immunodot; Indirect immunofluorescence