Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.


A New ELISA System for Detecting Autoantibodies to aminoacyl-tRNA Synthetases: Usefulness in Myositis and Interstitial Pneumonia.

Nakashima2,  Ran, Imura4,  Yoshitaka, Kobayashi3,  Shio, Hosono4,  Yuji, Yukawa4,  Naoichiro, Kawabata4,  Daisuke, Nojima4,  Takaki

Department of Rheumatology and Clinical Immunology, Kyoto University Graduate School of Medicine, Sakyo-ku Kyoto, Japan
Department of Rheumatology and Clinical Immunology, Kyoto University Graduate School of Medicine, Kyoto, Japan
Department of Rheumatology and Clinical Immunology, Kyoto University Graduate School of Medicine, Kyoto, Japan
Department of Rheumatology and Clinical Immunology, Kyoto University Graduate School of Medicine
Medical and Biological Laboratories CO., LTD
Medical and Biological Laboratories Co., Ltd., Nagano, Japan

Purpose:

Autoantibodies to aminoacyl-tRNA synthetases (ARS) are the most frequent myositis-specific antibodies and patients with anti-ARS antibodies show a spectrum of common clinical manifestations known as anti-synthetase syndrome. Detecting anti-ARS antibodies is useful in diagnosis, classification and management of polymyositis (PM)/dermatomyositis (DM) and interstitial pneumonia (IP). Immunoprecipitation assay is utilized currently to detect anti-ARS antibodies but can be done only in limited numbers of laboratories. For easy detection of anti-ARS antibodies, we established enzyme-linked immunosorbent assay (ELISA) system using a mixture of five known recombinant ARS antigens for detecting anti-Jo-1, anti-PL-7, anti-PL-12, anti-EJ and anti-KS antibodies at once.

Methods:

We prepared 6 recombinant ARS antigens; GST-Jo-1, His-PL-12, His-EJ and GST-KS expressed in E. coli, and His-PL-7 and His-OJ expressed in Trichoplusia Hi-5 cells. After confirming antigenic activity of all recombinant proteins except His-OJ using immunoblot and ELISA, we made an ELISA system using mixture of the five recombinant ARS. In order to confirm the efficiency of this newly established ELISA, we screened a total of 241 sera from patients with various connective tissue diseases (PM 57, DM 46 and other diseases 138), 62 from idiopathic IP (IIP) and 30 from healthy controls. The results of ELISA were compared with those of standard RNA immunoprecipitation assay.

Results:

Except for one false-negative and two false-positive samples, all of the results on anti-ARS positivity by ELISA were consistent with those by RNA immunoprecipitation. Sensitivity and specificity of the ELISA compared with RNA immunoprecipitation were 97.5% and 99.3%, respectively. Anti-ARS antibodies were detected in 33% (19/57) of PM, 28% (13/46) of DM, 2% (1/49) of SLE, 2% (1/49) of RA and 11% (7/62) of IIP. None of healthy controls was positive for anti-ARS antibodies. Among 32 anti-ARS-positive PM/DM patients, 30 (94%) had IP, 18 (56%) arthralgia, 12 (38%) fever, 12 (38%) Raynaud's phenomenon and 8 (25%) mechanic's hand. Two anti-ARS-positive patients either with SLE or RA revealed IP but no evidence of myositis.

Conclusion:

We established the new anti-ARS ELISA system using a mixture of five recombinant ARS antigens and demonstrated that it detected anti-ARS antibodies as efficiently as RNA immunoprecipitation. This system will make possible to detect anti-ARS antibodies in patients with PM/DM and IP more easily and be used widely in daily practice.

To cite this abstract, please use the following information:
Nakashima, Ran, Imura, Yoshitaka, Kobayashi, Shio, Hosono, Yuji, Yukawa, Naoichiro, Kawabata, Daisuke, et al; A New ELISA System for Detecting Autoantibodies to aminoacyl-tRNA Synthetases: Usefulness in Myositis and Interstitial Pneumonia. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :1377
DOI: 10.1002/art.29143

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