New aspects of clinical and immunological characteristics in patients with anti-asparaginyl tRNA synthetase (anti-KS) autoantibody

OBJECTIVES: Anti-asparaginyl tRNA synthetase (anti-KS) antibody is present in patients with interstitial lung disease (ILD) accompanied by polymyositis/dermatomyositis. We examined clinical/immunological features of these patients. METHODS: Polymyositis/dermatomyositis or ILD patients were screened for autoantibodies, and clinical/immunological data were collected retrospectively. ILD was diagnosed by computed tomography, and clinical/immunological features of anti-KS-positive patients were compared with those of anti-Jo-1-positive patients. RESULTS: Sixteen anti-KS-positive patients [female = 11; male = 5; average age 63.6 years (range, 40-81) years] were diagnosed: seven had ILD, four had clinically amyopathic DM (CADM) and ILD, three had Sjögren's syndrome (SS) and ILD one each had rheumatoid arthritis and ILD, or CADM/SS overlap and ILD. All patients had ILD with chronic onset and clinical course; 11/16 (69%) had nonspecific interstitial pneumonia, and five (31%) had usual interstitial pneumonia pattern. Regarding skin manifestations, 4 (27%) had typical DM rash and 11 (69%) had mechanic's hands. All anti-KS-positive patients had no clinical muscle weakness or serum creatine kinase elevation; 8/16 patients (50%) had sicca symptoms at a significantly high frequency compared with anti-Jo-1-positive patients (50% vs 11%, P = 0.01). CONCLUSIONS: Anti-KS-positive patients might form a distinguishable subset closely associated with sicca symptoms, CADM and chronic-type ILD with a relatively favourable prognosis.