Utility of myositis related antibodies in interstitial lung disease and suspected autoimmunity

Introduction: Myositis related antibodies (MRA) are helpful in the study of patients with idiopathic inflammatory myopathies (IIM), but their role in patients with interstitial lung disease (ILD) is unclear. The aim of this study is to assess whether MRA contribute to define diagnosis and / or determine change of treatment in a cohort of patients with ILD and to describe the clinical characteristics associated with a positive MRA. Methods: A panel of 16 MRA was performed on 111 patients with ILD who did not have a clear underlying diagnosis. The clinical baseline characteristics associated with a positive MRA were compared. Results: Half of patients had at least 1 positive MRA. There was a change in diagnosis in 27.9% of the patients and in the treatment of 62.3%. Ro-52 and anti-synthetase antibodies were the most frequent. The main rheumatological diagnoses were Anti-Synthetase syndrome, other IIM and ILD with autoimmune features (IPAF). The clinical characteristics that were associated with having a positive MRA were younger age, Raynaud´s, mechanical hands, anti Ro, and anti La. HRCT pattern of NSIP/OP and the absence of pattern of hypersensitivity showed a tendency to predict a positive MRA (Table 1). Conclusions: In the study of patients with ILD, testing MRA is specially useful in younger patients with some specific clinical features and specific HRCT patterns, and they contribute to change diagnosis and treatment.