The multicenter study of a new assay for simultaneous detection of multiple anti-aminoacyl-tRNA synthetases in myositis and interstitial pneumonia.
OBJECTIVE
Autoantibodies to aminoacyl-tRNA synthetases (ARSs) are useful in the diagnosis of idiopathic inflammatory myopathy (IIM) with interstitial pneumonia (IP). We developed an enzyme-linked immunosorbent assay (ELISA) system using a mixture of recombinant ARS antigens and tested its utility in a multicenter study.


METHODS
We prepared six recombinant ARSs: GST-Jo-1, His-PL-12, His-EJ and GST-KS expressed in Escherichia coli, and His-PL-7 and His-OJ expressed in Hi-5 cells. After confirming their antigenic activity, with the exception of His-OJ, we developed our ELISA system in which the five recombinant ARSs (without His-OJ) were mixed. Efficiency was confirmed using the sera from 526 Japanese patients with connective tissue disease (CTD) (IIM n = 250, systemic lupus erythematosus n = 91, systemic sclerosis n = 70, rheumatoid arthritis n = 75, Sjögren's syndrome n = 27 and other diseases n = 13), 168 with idiopathic interstitial pneumonia (IIP) and 30 healthy controls collected from eight institutes. IIPs were classified into two groups; idiopathic pulmonary fibrosis (IPF) (n = 38) and non-IPF (n = 130). RESULTS were compared with those of RNA immunoprecipitation.


RESULTS
Sensitivity and specificity of the ELISA were 97.1% and 99.8%, respectively when compared with the RNA immunoprecipitation assay. Anti-ARS antibodies were detected in 30.8% of IIM, 2.5% of non-myositis CTD, and 10.7% of IIP (5.3% of IPF and 12.3% of non-IPF). Anti-ARS-positive non-IPF patients were younger and more frequently treated with glucocorticoids and/or immunosuppressants than anti-ARS-negative patients.


CONCLUSIONS
A newly established ELISA detected anti-ARS antibodies as efficiently as RNA immunoprecipitation. This system will enable easier and wider use in the detection of anti-ARS antibodies in patients with IIM and IIP.
Department of Rheumatology and Clinical Immunology, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
Ran
R
Nakashima
Department of Rheumatology and Clinical Immunology, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
Yoshitaka
Y
Imura
Department of Rheumatology and Clinical Immunology, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
Yuji
Y
Hosono
Medical & Biological Laboratories Co., Ltd., Nagoya, Japan.
Minae
M
Seto
Medical & Biological Laboratories Co., Ltd., Nagoya, Japan.
Akihiro
A
Murakami
Department of Respiratory Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
Kizuku
K
Watanabe
Department of Respiratory Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
Tomohiro
T
Handa
Department of Respiratory Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
Michiaki
M
Mishima
Medical Education Center/Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan.
Michito
M
Hirakata
Division of Rheumatology, Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan.
Tsutomu
T
Takeuchi
Department of Allergy and Rheumatology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
Keishi
K
Fujio
Department of Allergy and Rheumatology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
Kazuhiko
K
Yamamoto
Department of Medicine and Rheumatology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
Hitoshi
H
Kohsaka
Department of Internal Medicine and Rheumatology, Juntendo University School of Medicine, Tokyo, Japan.
Yoshinari
Y
Takasaki
Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan.
Noriyuki
N
Enomoto
Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan.
Takafumi
T
Suda
Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan.
Kingo
K
Chida
Department of Respiratory Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan.
Shu
S
Hisata
Department of Respiratory Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan.
Toshihiro
T
Nukiwa
Department of Rheumatology and Clinical Immunology, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
Tsuneyo
T
Mimori
D000604:Amino Acyl-tRNA Synthetases / Q000276:immunology*; D001323:Autoantibodies / Q000097:blood* / Q000276:immunology*; D001324:Autoantigens / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D006801:Humans; D017563:Lung Diseases, Interstitial / Q000097:blood / Q000175:diagnosis*; D009220:Myositis / Q000175:diagnosis*
D001323:Autoantibodies; D001324:Autoantigens; D000604:Amino Acyl-tRNA Synthetases