Background/Purpose: Anti-KS antibody, an anti-aminoacyl tRNA synthetase (ARS) antibody, is found mainly in patients with interstitial lung disease (ILD) accompanied by polymyositis/dermatomyositis (PM/DM). Although anti-KS antibody has a stronger association with ILD compared with PM/DM, the clinical characteristics of anti-KS antibody have not been examined in detail. The aim of this study was to clarify the clinical and immunological features of patients with anti-KS antibody.

Methods: PM/DM or ILD patients who visited Tokai University Hospital between 2010 and 2018 were screened. Autoantibodies were identified by immunoprecipitation assays and all clinical and immunological data were collected retrospectively. ILD was diagnosed based on the findings of computed tomography. The clinical and immunological features of anti-KS positive patients were assessed. Comparisons between anti-KS positive patients and other anti-ARS positive patients were examined. Statistical analyses were performed using the Fisher’s exact test.

Results: Fifteen anti-KS positive patients were identified. Ten were female and 5 were male, with an average age of 62.5 years (range, 40-80 years). Final diagnoses were 6 patients with ILD alone, 4 with clinically amyopathic DM (CADM) and ILD, 3 with Sjögren’s Syndrome (SjS) and ILD, one each with rheumatoid arthritis (RA) and ILD, or CADM/SjS overlap and ILD. Although various diagnoses were determined for these patients, all patients had ILD with chronic onset and a chronic clinical course. Five patients (33%) presented with dyspnea as an initial symptom. On high-resolution computed tomography analysis, 10 (67%) of 15 patients revealed radiographic features of non-specific interstitial pneumonia (NSIP) and 4 (27%) had a usual interstitial pneumonia (UIP) pattern and one (7%) had an organizing pneumonia (OP) pattern. As for skin manifestations, 9 (60%) had mechanic’s hands, 4 (27%) had Gottron’s sign and one (7%) each had the heliotrope rash or palmar papules. Interestingly, all anti-KS positive showed no clinical muscle weakness or serum creatine kinase elevation. Moreover, seven of 15 patients (47%) had sicca syndrome and were positive for anti-SSA and/or anti-SSB antibodies. There was a significantly high frequency of sicca syndrome in anti-KS positive patients compared with anti-Jo-1 positive patients (47% vs. 12%, P=0.02).

Conclusion: These results suggest that anti-KS antibody positive patients might form a distinguishable subset that is closely associated with sicca syndrome and CADM as well as chronic type ILD.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/new-aspects-of-clinical-and-immunological-characteristics-in-patients-with-anti-ks-antibody/