Anti-aminoacyl-tRNA synthetase antibodies in clinical course prediction of interstitial lung disease complicated with idiopathic inflammatory myopathies. 
In the treatment of polymyositis and dermatomyositis (PM/DM), the complication of interstitial lung disease (ILD) is an important prognostic factor.  It has been reported that autoantibodies against aminoacyl-tRNA synthetases (ARS) are strongly associated with ILD.  The aim of this study is to examine the correlation between anti-ARS and the clinical course of ILD.  We investigated 41 cases of PM/DM with ILD.  The response of ILD to corticosteroids (CS) was determined according to the change in respiratory symptoms, image findings, and pulmonary function between, before and 2 months after the treatment.  Anti-ARS (anti-Jo-1, PL-7, PL-12, EJ, OJ and KS) antibodies were screened with the RNA immunoprecipitation assay.  In the stratification into ILD-preceding, simultaneous and myopathy-preceding types, anti-ARS antibodies were significantly frequent in the ILD-preceding type (p < 0.05).  In the stratification into anti-ARS-positive and negative groups, the response of ILD to CS was significantly better in the positive group (p < 0.05).  However, recurrence of ILD was significantly more frequent in the positive group (p < 0.01), and 2 year prognoses of pulmonary function (%VC and %DLCO) were not different between the two groups.  In conclusion, screening of anti-ARS may be useful to predict late-onset myopathy in ILD-preceding patients and to predict the clinical course of ILD in PM/DM patients.