Chest
Volume 135, Issue 6, June 2009, Pages 1550-1556
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Original Research
Interstitial Lung Disease
Clinical Profile of Anti-PL-12 Autoantibody: Cohort Study and Review of the Literature

https://doi.org/10.1378/chest.08-2233Get rights and content

Background

The antisynthetase syndrome consists of interstitial lung disease, arthritis, myositis, fever, mechanic's hands, and Raynaud phenomenon in the presence of an antisynthetase autoantibody, most commonly anti-Jo-1. It is believed that all the antisynthetases are associated with a similar clinical profile, but definitive data in this diverse group are lacking. The purpose of this study was to examine the clinical profile of anti-PL-12, an antisynthetase autoantibody directed against alanyl-transfer RNA synthetase.

Methods

Thirty-one subjects with anti-PL-12 autoantibody were identified from the databases at the Medical University of South Carolina, the University of Pittsburgh Medical Center, Johns Hopkins Medical Center, and Brigham and Women's Hospital. The medical charts were reviewed and the following data were recorded: demographic information; pulmonary and rheumatologic symptoms; connective tissue disease diagnoses; serologic autoantibody findings; CT scan results; BAL findings; pulmonary function test results; lung histopathology; and treatment interventions.

Results

The median age at symptom onset was 51 years; 81% were women and 52% were African American. Ninety percent of anti-PL-12-positive patients had ILD, 65% of whom presented initially to a pulmonologist. Ninety percent of anti-PL-12-positive patients had an underlying CTD. Polymyositis and dermatomyositis were the most common underlying diagnoses. Raynaud phenomenon occurred in 65% of patients, fever in 45% of patients, and mechanic's hands in 16% of patients. Test results for the presence of antinuclear antibody were positive in 48% of cases.

Conclusions

Anti-PL-12 is strongly associated with the presence of ILD, but less so with myositis and arthritis. Idiopathic ILD diagnosed as idiopathic pulmonary fibrosis may, in fact, be associated with anti-PL-12 and be a “forme fruste” of an underlying autoimmune disorder.

Section snippets

Materials and Methods

We performed a retrospective chart review of all anti-PL-12-positive patients at the following four tertiary care institutions: Medical University of South Carolina (MUSC); University of Pittsburgh Medical Center (UPMC); Johns Hopkins Medical Center (JHMC); and Brigham and Women's Hospital (BWH). Serologic testing was done at specialty laboratories by radio immunoprecipitation (IP) assay for MUSC and BWH. The sera at both UPMC and JHMC were analyzed by IP at university research laboratories. At

Results

Thirty-one patients with anti-PL-12 were identified (Table 2), as follows: UPMC, 14 patients; MUSC, 9 patients; JHMC, 5 patients; and BWH, 3 patients. The median age at diagnosis was 51 years (range, 22 to 87 years). There were 25 females (81%) and 16 African Americans (52%), 14 whites (45%), and 1 Hispanic patient (3%). Ninety percent had an underlying CTD. Ten patients (32%) had PM, 6 patients had DM (19%), and 5 patients (16%) had overlap syndromes with features of an IIM and a second CTD.

Discussion

The aminoacyl-tRNA synthetases are a group of ubiquitous cytoplasmic enzymes that play an important role in protein synthesis. Each cell has 20 different synthetases, one for each amino acid. The aminoacyl-tRNA synthetase enzyme recognizes its cognate amino acid, enabling correct sequencing within the polypeptide chain.5 Autoantibodies directed against these synthetases occur in the sera of 16 to 26% of adult patients with IIM and are considered specific to this disease.27 Anti-Jo-1, the first

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    Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestjournal.org/site/misc/reprints.xhtml).

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