Background/Purpose: Anti-Jo-1 antibody is an autoantibody specifically detected in sera of patients with polymyositis/dermatomyositis (PM/DM). The antigen corresponding to this autoantibody is histidyl-tRNA synthase, being an aminoacyl-tRNA synthase (ARS), which occurs in the cytoplasm of eukaryotes. Many autoantibodies directed to other ARS have been identified in recent years, and the condition of patients positive for these antibodies is currently termed anti-ARS antibody syndrome in that such condition is characterized by clinical features of pulmonary lesions and cutaneous manifestations. This study was performed to evaluate the clinical usefulness of determination of serum anti-ARS antibody levels in patients with PM/DM or other connective tissue diseases.

Methods: The study included 197 outpatients with connective tissue diseases at this hospital. Of them, 62 patients had PM/DM, 39 had systemic lupus erythematosus (SLE), 31 had rheumatoid arthritis (RA), 21 had Sjögren’s syndrome (SjS), 12 had progressive systemic sclerosis (SSc), 11 had mixed connective tissue disease (MCTD), 7 had vasculitis syndrome, 5 had Behçet’s disease, 4 had adult-onset Still’s disease, and 5 had other diseases. Determination of anti-ARS antibodies was carried out using Myositis Profile 3 Euroline Blot Test Kit commercially available from EUROIMMUN (Lubeck, Germany), in accordance with the manufacturer’s instructions. For each clinical entity concerned, anti-ARS antibody positivity rate, antinuclear antibody staining pattern, the presence/absence of concurrent interstitial pneumonia (IP), and dose levels of the corticosteroids or immunosuppressants used were assessed.

Results: Anti-ARS antibodies were detected with a significantly higher frequency among PM/DM patients with concurrent IP. Positivity for anti-ARS antibodies was observed even among RA patients with clinical signs of IP. Patients with PM/DM in whom cytoplasmic stain with antinuclear antibody was evident were frequently positive for anti-ARS antibodies other than anti-Jo-1 antibody even if they had negative results for this antibody. In patients negative for cytoplasmic staining, however, no other anti-ARS antibodies were detected. In patients with PM/DM complicated by IP positive for anti-ARS antibodies, the dosage of corticosteroids and percentage of patients receiving immunosuppressant therapy tended to be higher as compared with those negative for anti-ARS antibodies.

Conclusion: The present data suggest that the determination of serum anti-ARS antibody levels is clinically useful even in patients with IP-complicated connective tissue disease other than PM/DM. A strong association of the autoantibodies with pulmonary lesions was noted particularly in RA patients. The results also suggest that determination of serum anti-ARS antibody levels may be less necessary in myositis patients showing no positive cytoplasmic staining in the antinuclear antibody test using HEp-2.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/clinical-evaluation-of-anti-aminoacyl-trna-synthetase-antibodies-in-japanese-patients-with-connective-tissue-diseases/