Open AccessClinical and immunogenetic features of patients with autoantibodies to asparaginyl–transfer RNA synthetase
Author(s) -
Hirakata Michito,
Suwa Akira,
Takada Tetsuya,
Sato Shinji,
Nagai Sonoko,
Genth Ekkehard,
Song Yeong W.,
Mimori Tsuneyo,
Targoff Ira N.
Publication year - 2007
Publication title -
arthritis & rheumatism
Language(s) - English
Resource type - Journals
eISSN - 1529-0131
pISSN - 0004-3591
DOI - 10.1002/art.22506
Subject(s) - autoantibody , dermatomyositis , polymyositis , myositis , medicine , interstitial lung disease , antisynthetase syndrome , connective tissue disease , antibody , immunology , clinical significance , autoimmune disease , pathology , lung
Objective We have previously described anti‐KS autoantibodies and provided evidence that they are directed against asparaginyl–transfer RNA (tRNA) synthetase (AsnRS). The aim of the present study was to identify patients with anti‐AsnRS autoantibodies and elucidate the clinical significance of this sixth antisynthetase antibody. In particular, we studied whether it was associated with the syndrome of myositis (polymyositis or dermatomyositis [DM]), interstitial lung disease (ILD), arthritis, and other features that had been previously associated with the 5 other anti–aminoacyl–tRNA synthetase autoantibodies. Methods More than 2,500 sera from patients with connective tissue disease (including myositis and ILD) and controls were examined for anti‐AsnRS autoantibodies by immunoprecipitation (IP). Positive and control sera were tested for the ability to inhibit AsnRS by preincubation of the enzyme source with the serum. The HLA class II (DRB1, DQA1, DQB1, DPB1) alleles were identified from restriction fragment length polymorphism of polymerase chain reaction–amplified genomic DNA. Results Anti‐AsnRS antibodies were identified in the sera of 8 patients (5 Japanese, 1 American, 1 German, and 1 Korean) by IP of the same distinctive set of tRNA and protein that differed from those precipitated by the other 5 antisynthetases, and these antibodies showed specific inhibition of AsnRS activity. Two of these patients had DM, but 7 of 8 (88%) had ILD. Four patients (50%) had arthritis, and 1 had Raynaud's phenomenon. This antisynthetase was very rare among myositis patients (present in 0% of Japanese myositis patients), but it was found in 3% of Japanese ILD patients. Thus, most patients with anti‐AsnRS had chronic ILD with or without features of connective tissue disease. Interestingly, all 4 Japanese patients tested had DR2 (DRB1*1501/1502), compared with 33% of healthy controls. Conclusion These results indicate that anti‐AsnRS autoantibodies, like anti–alanyl–tRNA synthetase autoantibodies, have a stronger association with ILD than with myositis and may be associated with the DR2 phenotype.