Objectives Anti-Jo-1 antibody is an autoantibody specifically detected in the serum of patients with polymyositis (PM) or dermatomyositis (DM). The homologous antigen of anti-Jo-1 antibody is a histidyl tRNA synthetase, one of the aminoacyl tRNA synthetases (ARS) found in cytoplasm. A number of antibodies homologous to other ARSs have been identified recently. Lung and skin diseases observed characteristically in patients with anti-Jo-1 antibody are collectively called anti-ARS antibody syndrome. We measured the anti-ARS antibody level in rheumatoid arthritis (RA) patients and evaluated the clinical characteristics of their symptoms.
Methods This study included 234 RA outpatients treated at our clinic to evaluate their anti-ARS antibody level, antinuclear antibody prevalence and staining pattern, concurrent interstitial pneumonia (IP), joint symptoms and Raynaud's phenomenon, concurrent PM/DM, and medications including biological drugs. The anti-ARS antibody level was measured using Myositis Profile 3 EUROLINE (EUROIMMUNE, Lubeck, Germany) according to the manufactures instructions.
Results Anti-ARS antibodies were detected in 18 patients (7.7%). Specifically, anti-PL-7 antibody was detected in 7 patients (3.0%), anti-EJ antibody was detected in 6 patients (2.6%), anti-Jo-1 antibody was detected in 2 patient (0.9%), anti-PL-12 antibody was detected in 2 patients (0.9%), and anti-OJ antibody was detected in 1 patient (0.4%). The evaluation of clinical characteristics found concurrent IP in 42.8% of anti-EJ antibody-positive patients, no anti-OJ antibody-positive patients, 71.4% of anti-PL-7 antibody-positive patients, and all anti-PL-12 antibody-positive patients. The results suggest anti-PL-12 antibody and anti-PL-7 antibody are IP-related autoantibodies. In patients with concurrent IP, the prevalence was significantly high (33.3%). The evaluation of non-IP clinical presentations in anti-ARS antibody positive patients found no noteworthy characteristics such as arthritis, skin symptoms, and use of specific medications. Biological drugs were used in 3 anti-ARS antibody-positive patients safely without inducing myositis or aggravating IP.
Conclusions Of the anti-ARS antibodies specifically detected in PM/DM patients, anti-PL-7 and anti-PL-12 antibodies were detected in RA patients with concurrent IP at a significantly high frequency, suggesting these autoantibodies are associated with IP. Biological drugs may be used safely in patients tested positive for these autoantibodies.
Disclosure of Interest None declared
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