ACR Meeting Abstracts

ACR Meeting Abstracts

Abstract Number: 1938

A New Enzyme-Linked Immunosorbent Assay System for Detecting Autoantibodies to Aminoacyl-tRNA Synthetases: Clinical Usefulness in Myositis and Interstitial Pneumonia

Ran Nakashima1, Yoshitaka Imura2, Minae Seto3, Akihiro Murakami3, Yuji Hosono4, Kizuku Watanabe5, Tomohiro Handa5, Michiaki Mishima5, Michito Hirakata6, Tsutomu Takeuchi7, Keishi Fujio8, Kazuhiko Yamamoto9, Hitoshi Kohsaka10, Yoshinari Takasaki11, Noriyuki Enomoto12, Kingo Chida12, Toshihiro Nukiwa13 and Tsuneyo Mimori1, 1Department of Rheumatology and Clinical Immunology, Graduate School of Medicine, Kyoto University, Kyoto, Japan, 2Rheumatology and Clinical Immunology, Kyoto University Graduate School of Medicine, Kyoto, Japan, 3Medical & Biological Laboratories Co., Ltd., Ina, Japan, 4Department of Rheumatology and Clinical Immunology, Kyoto University Graduate School of Medicine, Kyoto, Japan, 5Department of Respiratory Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan, Kyoto, Japan, 6Internal Medicine, Keio University, Tokyo, Japan, 7Keio University School of Medicine, Tokyo, Japan, 8Department of Allergy and Rheumatology, The University of Tokyo, Tokyo, Japan, 9Department of Allergy & Rheumatology, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo, Japan, 10Department of Medicine and Rheumatology, Tokyo Medical and Dental University, Tokyo, Japan, 11Division of Rheumatology, Department of Internal Medicine, Juntendo University, Tokyo, Japan, 12Hamamatsu University School of Medicine, Hamamatsu, Japan, 13Department of Respiratory Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan

Meeting: 2012 ACR/ARHP Annual Meeting

Keywords: , ,

Session Information

Title: Muscle Biology, Myositis and Myopathies: Genetics, Autoantibodies and other Molecular Aspects of Idiopathic Inflammatory Myopathies and Models

Session Type: Abstract Submissions (ACR)

Background/Purpose: Autoantibodies to aminoacyl-tRNA synthetases (ARS) are the most frequent myositis-specific antibodies and they are useful in the diagnosis and management of polymyositis (PM)/ dermatomyositis (DM) and interstitial pneumonia (IP). However, routine detection of all of them at once is not available. We developed an enzyme-linked immunosorbent assay (ELISA) system using a mixture of recombinant ARS antigens to detect them easily and simultaneously. We tested the usefulness of this system for diagnosing PM/DM and IP in the multicenter study.

Methods:  We prepared 6 recombinant ARS antigens; GST-Jo-1, His-PL-12, His-EJ and GST-KS expressed in Eschericha coli, and His-PL-7 and His-OJ expressed in Hi-5 cells. After confirming antigenic activity of all the recombinant proteins except His-OJ, using immunoblotting or ELISA, we made an ELISA system mixing the five recombinant ARS antigens. Efficiency was confirmed using the sera from 549 Japanese patients with various connective tissue diseases (PM/DM 273, systemic lupus erythematosus (SLE) 91, systemic sclerosis (SSc) 70, rheumatoid arthritis (RA) 75, Sjӧgren’s syndrome (SS) 27 and other diseases 13), 170 idiopathic IP (IIP) and 30 healthy controls collected from 8 institutes. IIP was classified into two groups according to the radiologic pattern, usual interstitial pneumonia (UIP) (n=36) and non-UIP (n=132). Results were compared with those of the standard RNA immunoprecipitation assay.

Results: All of the ELISA results were consistent with those of the immunoprecipitation assay, except for one false-positive sample. Sensitivity and specificity were 100% and 99.8%, respectively when compared with the RNA immunoprecipitation. Anti-ARS antibodies were detected in 34.8% of PM/DM, 2.2% of SLE, 2.9% of SSc, 4% of RA, 0% of SS and 10.6% of IIP. None of the healthy controls were positive for anti-ARS antibodies. The frequency of each anti-ARS antibodies was compatible with previous reports. Anti-ARS-positive PM/DM patients had IP much more frequently than anti-ARS-negative PM/DM patients (87.3% vs. 48.6% respectively, p<0.001). In IIP, anti-ARS antibodies were positive in 5.6% of UIP and 12.1% of non-UIP. Anti-ARS-positive IIP patients were younger and more frequently treated with corticosteroids and/or immunosuppressants than anti-ARS-negative patients.

Conclusion: A newly established anti-ARS ELISA system detected anti-ARS antibodies as efficiently as RNA immunoprecipitation. This system will enable the easier and wider detection of anti-ARS antibodies in patients with PM/DM and IP in daily practice.

Disclosure:

R. Nakashima,
None;

Y. Imura,
None;

M. Seto,

Medical & Biological Laboratories, Co., Ltd.,

3;

A. Murakami,

Medical & Biological Laboratories, Co., Ltd.,

3;

Y. Hosono,
None;

K. Watanabe,
None;

T. Handa,
None;

M. Mishima,
None;

M. Hirakata,
None;

T. Takeuchi,
None;

K. Fujio,
None;

K. Yamamoto,
None;

H. Kohsaka,

Chugai Pharma, Ajinomoto Pharma & Teijin Parma,

5;

Y. Takasaki,
None;

N. Enomoto,
None;

K. Chida,
None;

T. Nukiwa,
None;

T. Mimori,

Medical & Biological Laboratories, Co., Ltd.,

2,

Medical & Biological Laboratories, Co., Ltd,

8.

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