Unusually high frequency of autoantibodies to PL-7 associated with milder muscle disease in Japanese patients with polymyositis/dermatomyositis.
OBJECTIVE
Autoantibodies to aminoacyl transfer RNA synthetases, such as histidyl (Jo-1), threonyl (PL-7), alanyl (PL-12), glycyl (EJ), and isoleucyl (OJ), are closely associated with a subset of patients with polymyositis/dermatomyositis (PM/DM) complicated by interstitial lung disease (ILD). Anti-Jo-1 is by far the most common, found in 15-25% of patients with PM/DM, whereas the other types are found in only approximately 3% of these patients. In this study, the clinical associations of these autoantibodies in Japanese patients with PM/DM were investigated.


METHODS
The diagnoses of PM/DM and amyopathic DM (ADM) were based on the Bohan and Peter criteria and Sontheimer's definition, respectively. Sera from 36 Japanese patients with PM/DM (13 with PM, 20 with DM, 3 with ADM) were screened by immunoprecipitation and by enzyme-linked immunosorbent assay (for Jo-1). Clinical and laboratory data were collected.


RESULTS
The frequencies of autoantibodies to Jo-1 (22%) and to EJ, OJ, and PL-12 (3-6%) were similar to those found in previous studies, including studies of Japanese subjects. However, anti-PL-7 was found in 17% of patients, in contrast to a frequency of 1-4% in previous studies (P < 0.02-0.0002). The 6 anti-PL-7-positive patients were not related, and no skewing in year or month of disease development, place of residence or work, or occupation was found. All patients had ILD, consistent with the clinical features of antisynthetase-positive patients. The patients with anti-PL-7 had lower serum muscle enzyme levels and milder muscle weakness (P < 0.05) compared with anti-Jo-1-positive patients.


CONCLUSIONS
Anti-PL-7 was found at an unusually high frequency in this group of Japanese patients with myositis. Although anti-PL-7, similar to anti-Jo-1, is associated with PM/DM with ILD, muscle involvement in the patients with anti-PL-7 appeared to be milder than that in the anti-Jo-1 subset.
Yamasaki
Yoshioki
Y
University of Florida, Gainesville, USA.
Yamada
Hidehiro
H
Nozaki
Toshiko
T
Akaogi
Jun
J
Nichols
Cody
C
Lyons
Robert
R
Loy
Anthony Chin
AC
Chan
Edward K L
EK
Reeves
Westley H
WH
Satoh
Minoru
M
D000328:Adult; D000412:Alanine-tRNA Ligase / Q000276:immunology; D044466:Asian People; D001323:Autoantibodies / Q000097:blood*; D003882:Dermatomyositis / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006032:Glycine-tRNA Ligase / Q000276:immunology; D006643:Histidine-tRNA Ligase / Q000276:immunology; D006801:Humans; D047468:Immunoprecipitation; D007533:Isoleucine-tRNA Ligase / Q000276:immunology; D007564:Japan; D017563:Lung Diseases, Interstitial / Q000150:complications; D008297:Male; D008875:Middle Aged; D009135:Muscular Diseases / Q000276:immunology; D017285:Polymyositis / Q000276:immunology; D013914:Threonine-tRNA Ligase / Q000276:immunology*
D001323:Autoantibodies; D006032:Glycine-tRNA Ligase; D006643:Histidine-tRNA Ligase; D013914:Threonine-tRNA Ligase; D007533:Isoleucine-tRNA Ligase; D000412:Alanine-tRNA Ligase