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 (PM/DM). We examined clinical/immunological features of these patients.

METHODS: PM/DM 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 anti-Jo-1 positive patients.

RESULTS: Sixteen anti-KS positive patients (female=11; male=5; average age 63.6 years (range, 40-81)) were diagnosed: 7 had ILD, 4 had clinically amyopathic DM (CADM) and ILD, 3 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 non-specific interstitial pneumonia, 5 (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 favorable prognosis.