PT  - JOURNAL ARTICLE
AU  - Vulsteke, Jean-Baptiste
AU  - Derua, Rita
AU  - Dubucquoi, Sylvain
AU  - Coutant, Frédéric
AU  - Sanges, Sebastien
AU  - Goncalves, David
AU  - Wuyts, Greet
AU  - De Haes, Petra
AU  - Blockmans, Daniel
AU  - Wuyts, Wim A
AU  - Claeys, Kristl G
AU  - De Langhe, Ellen
AU  - Fabien, Nicole
AU  - Bossuyt, Xavier
TI  - Mass spectrometry-based identification of new anti-Ly and known antisynthetase autoantibodies
AID  - 10.1136/ard-2022-222686
DP  - 2023 Apr 01
TA  - Annals of the Rheumatic Diseases
PG  - 546--555
VI  - 82
IP  - 4
4099  - http://ard.bmj.com/content/82/4/546.short
4100  - http://ard.bmj.com/content/82/4/546.full
SO  - Ann Rheum Dis2023 Apr 01; 82
AB  - Objectives To discover new and detect known antisynthetase autoantibodies (ASAs) through protein immunoprecipitation combined with gel-free liquid chromatography-tandem mass spectrometry (IP-MS).Methods IP-MS was performed using sera of individuals showing features of antisynthetase syndrome (ASyS) without (n=5) and with (n=12) previously detected ASAs, and healthy controls (n=4). New candidate aminoacyl-tRNA-synthetase (ARS) autoantigens identified through unbiased IP-MS were confirmed by IP-western blot. A targeted IP-MS assay for various ASA specificities was developed and validated with sera of patients with known ASAs (n=16), disease controls (n=20) and healthy controls (n=25). The targeted IP-MS assay was applied in an additional cohort of patients with multiple ASyS features or isolated myositis without previously detected ASAs (n=26).Results Autoantibodies to cytoplasmic cysteinyl-tRNA-synthetase (CARS1) were identified by IP-MS and confirmed by western blot as a new ASA specificity, named anti-Ly, in the serum of a patient with ASyS features. Rare ASAs, such as anti-OJ, anti-Zo and anti-KS, and common ASAs could also be identified by IP-MS. A targeted IP-MS approach for ASA detection was developed and validated. Application of this method in an additional cohort identified an additional patient with anti-OJ autoantibodies that were missed by line and dot immunoassays.Discussion CARS1 is the dominant cognate ARS autoantigen of the newly discovered anti-Ly ASA specificity. Rare and common ASA specificities could be detected by both unbiased and targeted IP-MS. Unbiased and targeted IP-MS are promising methods for discovery and detection of autoantibodies, especially autoantibodies that target complex autoantigens.Data are available on reasonable request.