title: Anti-Jo-1 antibody levels correlate with disease activity in idiopathic inflammatory myopathy.
abstract: OBJECTIVE
  Previous case series have examined the relationship between anti-Jo-1 antibody levels and myositis disease activity, demonstrating equivocal results. Using enzyme-linked immunosorbent assays (ELISAs) and novel measures of myositis disease activity, the current study was undertaken to systematically reexamine the association between anti-Jo-1 antibody levels and various disease manifestations of myositis.
  
  
  METHODS
  Serum anti-Jo-1 antibody levels were quantified using 2 independent ELISA methods, while disease activity was retrospectively graded using the Myositis Disease Activity Assessment Tool, which measures disease activity in 7 different organ systems via the Myositis Disease Activity Assessment Visual Analog Scale (VAS) and the Myositis Intention-to-Treat Index (MITAX) components. Spearman's rank correlation coefficients and mixed linear regression analysis were used to identify associations between anti-Jo-1 antibody levels and organ-specific disease activity in cross-sectional and longitudinal analyses, respectively.
  
  
  RESULTS
  Cross-sectional assessment of 81 patients with anti-Jo-1 antibody revealed a modest correlation between the anti-Jo-1 antibody level and the serum creatine kinase (CK) level, as well as muscle and joint disease activity. Correlation coefficients were similar for CK levels (r(s) = 0.38, P = 0.002), myositis VAS (r(s) = 0.36, P = 0.002), and arthritis VAS (r(s) = 0.40, P = 0.001). In multiple regression analyses of 11 patients with serial samples, anti-Jo-1 antibody levels correlated significantly with CK levels (R(2) = 0.65, P = 0.0002), myositis VAS (R(2) = 0.53, P = 0.0008), arthritis VAS (R(2) = 0.53, P = 0.006), pulmonary VAS (R(2) = 0.69, P = 0.005), global VAS (R(2) = 0.63, P = 0.002), and global MITAX (R(2) = 0.64, P = 0.0003).
  
  
  CONCLUSIONS
  In this large series of patients with idiopathic inflammatory myopathy, anti-Jo-1 antibody levels correlated modestly with muscle and joint disease, an association confirmed by a custom ELISA using recombinant human Jo-1. More striking associations emerged in a smaller longitudinal subset of patients that link anti-Jo-1 antibody levels to muscle, joint, lung, and global disease activity.
authors.affiliation: University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, USA.
authors.forename: Kerry B
authors.initials: KB
authors.lastname: Stone
authors.forename: Chester V
authors.initials: CV
authors.lastname: Oddis
authors.forename: Noreen
authors.initials: N
authors.lastname: Fertig
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Katsumata
authors.forename: Mary
authors.initials: M
authors.lastname: Lucas
authors.forename: Molly
authors.initials: M
authors.lastname: Vogt
authors.forename: Robyn
authors.initials: R
authors.lastname: Domsic
authors.forename: Dana P
authors.initials: DP
authors.lastname: Ascherman
mesh_terms: D000328:Adult; D000368:Aged; D001323:Autoantibodies / Q000097:blood*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006643:Histidine-tRNA Ligase / Q000276:immunology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009220:Myositis / Q000097:blood* / Q000276:immunology*; D012189:Retrospective Studies
chemical_list: D001323:Autoantibodies; D006643:Histidine-tRNA Ligase