Clinical evaluation of anti-aminoacyl tRNA synthetase antibodies in Japanese patients with dermatomyositis.

OBJECTIVE

To investigate the distribution of anti-aminoacyl-tRNA synthetase (anti-ARS) antibodies among patients with autoimmune diseases, and to analyze the clinical features of patients with dermatomyositis (DM) with anti-ARS antibodies.

METHODS

Serum samples from 315 patients with autoimmune diseases or related disorders who had visited Kanazawa University Hospital or affiliated facilities were assessed for anti-ARS antibodies by immunoprecipitation. In particular, the association between anti-ARS antibodies and clinical features was investigated in detail in patients with DM.

RESULTS

Anti-ARS antibody was positive in 16 (29%) of 55 patients with DM, 2 (22%) of 9 patients with polymyositis, and 7 (25%) of 28 patients with idiopathic pulmonary fibrosis. Although anti-ARS antibody was detected with high frequency (63%, 15/24) in DM patients with interstitital lung disease (ILD), the incidence of anti-ARS antibody was very low (3%, 1/31) in DM patients without ILD. Anti-ARS antibody-positive patients with DM had significantly higher incidences of ILD (94% vs 23%) and fever (64% vs 10%) than the antibody-negative patients. Some immunosuppressive agents, in addition to oral corticosteroids, were required more frequently in the antibody-positive patients with DM than the antibody-negative patients (88% vs 26%). Although 60% of DM patients with ILD simultaneously developed ILD and myositis, ILD preceded myositis in 33% of patients.

CONCLUSION

Among patients with DM, anti-ARS antibodies are found in a subset with ILD. DM patients with anti-ARS antibodies appear to have a more persistent disease course that requires additional therapy compared to those without anti-ARS antibodies.