Characteristics of Antisynthetase Syndrome with Anti-threonyl tRNA Synthetase Antibody

  Objective  To describe the clinical, laboratory, and radiographic characteristics of antisynthetase syndrome (ASS) patients with anti-threonyl tRNA synthetase (anti-PL-7) antibody.

  Methods  The clinical, laboratory, and radiographic data of five ASS cases with positive anti-PL-7 antibody hospitalized in Peking Union Medical College Hospital from August 2010 to December 2011 were retrospectively analyzed.

  Results  All these five patients demonstrated myositis, including symmetrical proximal muscle weakness (4/5), increased serum creatine phosphokinase (5/5), myogenic damage on electromyography (4/5), and positive results on biopsy (3/3). Four patients met the classification criteria for polymyositis (PM), and one patient presented typical rash of dermatomyositis (DM). Four patients had fever at onset, and two patients showed inflammatory arthritis. None of these patients developed Raynaud phenomenon or mechanic hands. Four patients demonstrated a cytoplasmic pattern when testing for antinuclear antibodies by immunofluorescent assay, and all had anti-PL-7 antibodies. Three patients had positive anti-Ro-52 antibodies. All patients had evidence of interstitial lung disease (ILD) by clinical examination, imaging, or pulmonary function testing. Four patients presented dry cough, gradual dyspnea, and crackles at lung base. Three patients presented with a restrictive pulmonary pattern and impaired gas exchange. High-resolution computed tomography scan revealed (predominantly basilar) reticular and ground-glass opacities, accompanied by a loss of lung volume, traction bronchiectasis, and scattered (usually peribronchovascular) areas of consolidation. This distinct pattern is highly suggestive of ASS-related ILD. Patients were responsive to high-dose corticosteroid plus cyclophosphamide and/or methotrexate.

  Conclusion  Anti-PL-7 antibody is closely associated with PM/DM with ILD, which may be accompanied with fever and arthritis. Treatment with high-dose glucocorticosteroid and immunosuppressants may result in good response.