title: Clinical manifestations in patients with antibody to PL-12 antigen (alanyl-tRNA synthetase).
abstract: OBJECTIVE
  Anti-PL-12 antibody is directed at the enzyme alanyl-tRNA synthetase (ARS). Studies have clearly associated anti-Jo-1, also directed at an aminoacyl-tRNA synthetase (histidyl-tRNA synthetase), with a subgroup of myositis marked by a high frequency of interstitial lung disease (ILD) and arthritis. A similar syndrome has been reported in patients with antibodies to PL-12, but few patients have been studied. We describe the clinical manifestations in a new series of patients with antibody to PL-12.
  
  
  METHODS
  Sera from patients with polymyositis and sera found to contain anticytoplasmic antibodies were screened for antibody to PL-12 by testing for inhibition of ARS enzymatic activity by serum, and by immunoprecipitation.
  
  
  RESULTS
  Nine sera inhibited ARS. These nine plus two additional sera with anticytoplasmic antibodies immunoprecipitated an identical pattern of tRNAs and a polypeptide of 110 kd. Of the 10 patients that could be evaluated, eight had some evidence of myositis, including six that satisfied the criteria for myositis. Three of these six, all with dermatomyositis, had severe muscle involvement. Eight of the 10 patients had radiographic evidence of pulmonary fibrosis, and seven of the eight had clinical pulmonary impairment, including four with clinically severe ILD. Joint manifestations were found in five patients, and arthritis was the only clinical problem in one patient.
  
  
  CONCLUSIONS
  We conclude that anti-PL-12, like anti-Jo-1 and anti-PL-7, was frequently associated with the "Jo-1 syndrome" of myositis with ILD. ILD was a major clinical problem in this group of patients.
authors.affiliation: Department of Medicine, Oklahoma University Health Science Center, Oklahoma City.
authors.forename: I N
authors.initials: IN
authors.lastname: Targoff
authors.forename: F C
authors.initials: FC
authors.lastname: Arnett
mesh_terms: D000328:Adult; D000412:Alanine-tRNA Ligase / Q000276:immunology*; D000604:Amino Acyl-tRNA Synthetases / Q000276:immunology*; D001323:Autoantibodies / Q000276:immunology* / Q000302:isolation & purification; D005260:Female; D006801:Humans; D007158:Immunologic Techniques; D008297:Male; D008875:Middle Aged; D009220:Myositis / Q000150:complications / Q000276:immunology*; D011233:Precipitin Tests; D011658:Pulmonary Fibrosis / Q000150:complications / Q000503:physiopathology; D012129:Respiratory Function Tests
chemical_list: D001323:Autoantibodies; D000604:Amino Acyl-tRNA Synthetases; D000412:Alanine-tRNA Ligase