{ "abstract": "Introduction The identification of specific autoantibodies can aid in the diagnosis, prognosis and management of systemic sclerosis (SSc). Commercial solid phase assays (including line blots and dot blots) are widely used for detection of SSc-specific and SSc-associated antibodies but may suffer from poor sensitivity or specificity for certain antibody specificities. Moreover, not all SSc-specific/associated antibodies can be detected by commercial assays, leaving a seronegative gap of ~10-15%. We aimed to characterize the antibodies that remained unidentified by commercial solid phase assays using immunoprecipitation combined with mass spectrometry (IP-MS). With IP-MS, antibodies can interact with epitopes of proteins or protein complexes, which can be directly identified through MS analysis without the need for an intermediary gel-based step.Material and Methods We analyzed samples from 135 patients diagnosed with SSc or SSc-myositis overlap syndrome with unknown autoantibodies from 8 cohorts [Cliniques Universitaires Saint-Luc (Belgium, n = 44), University of Calgary (Canada, n = 33), Chris Hani Baragwanath Hospital (South Africa, (n = 19), Centre Hospitalier Universitaire d’Angers (France, n = 11), Centre Hospitalier Lyon Sud (France, n = 11), Centre Hospitalier Universitaire de Lyon (France, n = 11), Nippon Medical School (Japan, n = 5) and University Medical Centre Ljubljana (Slovenia, n = 3) using IP-MS.Results SSc-specific/associated autoantibodies targeting Th/To (n = 19), RNA polymerase III (n = 8), Scl-70/topoisomerase 1 (n = 5), fibrillarin (n = 6) were identified in 37 patients. In 24 other patients SSc-myositis overlap syndrome-associated autoantibodies targeting PM/Scl (n=7), Ku (n=1), U1-RNP (n=9) and RuvBL1/2 (n=5, 1 patient also had anti-Th/To antibodies) were detected. In addition, autoantibodies against several rare SSc-associated autoantigens like the THO complex (n = 2), NVL (n = 3), RCC1 (n = 2), NOLC1 (n = 1) and NOP2 (n = 1) were identified. Two patients presented with myositis-specific autoantibodies (anti-Mi-2 and anti-Jo1). In three patients anti-mitochondrial autoantibodies were detected and in one patient anti-PCNA. Finally, in 5 other patients possible novel autoantibodies were identified. In total, an autoantibody could be identified in 56% of previously seronegative patients.Conclusions IP-MS identified autoantibodies in more than half of individuals with SSc or SSc-myositis overlap with previously unknown antibody specificity.Abstract P.040 Figure 1", "authors": [ { "affiliations": [ "KU Leuven, Clinical and Diagnostic Immunology, Leuven, Belgium", "University Hospitals Leuven, Laboratory Medicine, Leuven, Belgium" ], "name": "Birthe Michiels" }, { "affiliations": [ "KU Leuven, Clinical and Diagnostic Immunology, Leuven, Belgium", "University Hospitals Leuven, Rheumatology, Leuven, Belgium", "AZ Delta, Rheumatology, Roeselare, Belgium" ], "name": "Jean-Baptiste Vulsteke" }, { "affiliations": [ "Cliniques Universitaires Saint-Luc, Rheumatology, Brussels, Belgium", "Centre Hospitalier Universitaire Mont Godinne, Yvoir, Belgium", "European Reference Network on Rare and Complex Connective Tissue Diseases, * OTHER" ], "name": "Marie Vanthuyne" }, { "affiliations": [ "University of Calgary, Department of Medicine, Cumming School of Medicine, Calgary, Canada" ], "name": "May Choi" }, { "affiliations": [ "KU Leuven, Clinical and Diagnostic Immunology, Leuven, Belgium", "University Hospitals Leuven, Laboratory Medicine, Leuven, Belgium", "University Hospitals Leuven, Rheumatology, Leuven, Belgium", "AZ Delta, Rheumatology, Roeselare, Belgium", "Cliniques Universitaires Saint-Luc, Rheumatology, Brussels, Belgium", "Centre Hospitalier Universitaire Mont Godinne, Yvoir, Belgium", "European Reference Network on Rare and Complex Connective Tissue Diseases, * OTHER", "University of Calgary, Department of Medicine, Cumming School of Medicine, Calgary, Canada", "University of the Witwatersrand, Internal Medicine, Johannesburg, SOUTH AFRICA", "Centre Hospitalier Universitaire d’Angers, Internal Medicine, Angers, France", "Centre Hospitalier Lyon Sud, Hospices Civils de Lyon, Immunology, Lyon, France", "University of Lyon, Immunogenomics and Inflammation Research Team, Lyon, France", "University Medical Centre Ljubljana, Rheumatology, Ljubljana, Slovenia", "University of Primorska, Faculty of Mathematics, Natural Sciences and Information Technologies, Koper, Slovenia", "KU Leuven, Skeletal Biology and Engineering Research Center, Leuven, Belgium", "University of Ljubljana, Faculty of Pharmacy, Ljubljana, Slovenia", "Centre Hospitalier Universitaire d’Angers, Laboratoire d’Immunology et d’Allergologie, Angers, France", "University of Bath, Department of Life Sciences, Bath, United Kingdom" ], "name": "Canadian Scleroderma Research Group" }, { "affiliations": [ "University of the Witwatersrand, Internal Medicine, Johannesburg, SOUTH AFRICA" ], "name": "Tikly Mohammed" }, { "affiliations": [ "University of Calgary, Department of Medicine, Cumming School of Medicine, Calgary, Canada" ], "name": "Carole Lacout" }, { "affiliations": [ "Centre Hospitalier Universitaire d’Angers, Internal Medicine, Angers, France" ], "name": "Antoine Brochard" }, { "affiliations": [ "Centre Hospitalier Lyon Sud, Hospices Civils de Lyon, Immunology, Lyon, France", "University of Lyon, Immunogenomics and Inflammation Research Team, Lyon, France" ], "name": "Frédéric Coutant" }, { "affiliations": [ "University Medical Centre Ljubljana, Rheumatology, Ljubljana, Slovenia", "University of Primorska, Faculty of Mathematics, Natural Sciences and Information Technologies, Koper, Slovenia" ], "name": "Katja Lakota" }, { "affiliations": [ "University Hospitals Leuven, Rheumatology, Leuven, Belgium", "European Reference Network on Rare and Complex Connective Tissue Diseases, * OTHER", "KU Leuven, Skeletal Biology and Engineering Research Center, Leuven, Belgium" ], "name": "Ellen De Langhe" }, { "affiliations": [ "KU Leuven, Clinical and Diagnostic Immunology, Leuven, Belgium" ], "name": "Doreen Dillaerts" }, { "affiliations": [ "KU Leuven, Clinical and Diagnostic Immunology, Leuven, Belgium" ], "name": "Tom Dehaemers" }, { "affiliations": [ "KU Leuven, Clinical and Diagnostic Immunology, Leuven, Belgium", "University Hospitals Leuven, Rheumatology, Leuven, Belgium" ], "name": "Jonas De Leeuw" }, { "affiliations": [ "University Medical Centre Ljubljana, Rheumatology, Ljubljana, Slovenia", "University of Ljubljana, Faculty of Pharmacy, Ljubljana, Slovenia" ], "name": "Sasa Cucnik" }, { "affiliations": [ "Centre Hospitalier Lyon Sud, Hospices Civils de Lyon, Immunology, Lyon, France" ], "name": "Nicole Fabien" }, { "affiliations": [ "Centre Hospitalier Universitaire d’Angers, Laboratoire d’Immunology et d’Allergologie, Angers, France" ], "name": "Emeline Vinatier" }, { "affiliations": [ "University of Bath, Department of Life Sciences, Bath, United Kingdom" ], "name": "Neil McHugh" }, { "affiliations": [ "University of Bath, Department of Life Sciences, Bath, United Kingdom" ], "name": "Sarah Tansley" }, { "affiliations": [ "University of Calgary, Department of Medicine, Cumming School of Medicine, Calgary, Canada" ], "name": "Marvin J Fritzler" }, { "affiliations": [ "Cliniques Universitaires Saint-Luc, Rheumatology, Brussels, Belgium", "European Reference Network on Rare and Complex Connective Tissue Diseases, * OTHER" ], "name": "Frédéric Houssiau" }, { "affiliations": [ "KU Leuven, Clinical and Diagnostic Immunology, Leuven, Belgium", "University Hospitals Leuven, Laboratory Medicine, Leuven, Belgium" ], "name": "Xavier Bossuyt" } ], "title": "P.040 Closing the seronegative gap in systemic sclerosis with immunoprecipitation–mass spectrometry: a multicentric international study", "uid": "f021b3b6-61cb-5f34-9f85-044c427e314b" }