title: Prevalence and clinical significance of circulating autoantibodies in idiopathic pulmonary fibrosis.
abstract: BACKGROUND
  The clinical significance of circulating autoantibodies in idiopathic pulmonary fibrosis is unclear. The objective of this study was to determine the frequency and clinical significance of circulating autoantibodies in idiopathic pulmonary fibrosis.
  
  
  METHODS
  We measured an extensive panel of autoantibodies (including rheumatoid factor, anti-cyclic citrullinated peptide, and anti-nuclear antibodies by immunofluorescence) associated with connective tissue disease or vasculitis in a cohort of well-characterized patients with idiopathic pulmonary fibrosis (n = 67). The prevalence of circulating autoantibodies was compared between idiopathic pulmonary fibrosis patients and healthy controls (n = 52). We compared the clinical characteristics of patients with and without circulating autoantibodies, and analyzed the relationship between autoantibody positivity and transplant-free survival time.
  
  
  RESULTS
  Positive autoantibodies were found in 22% of patients with IPF and 21% of healthy controls. There were no differences in the types of autoantibodies found between patients with idiopathic pulmonary fibrosis and healthy controls. Among patients with idiopathic pulmonary fibrosis, there were no significant differences in clinical characteristics between those with and without circulating autoantibodies. The presence of circulating autoantibodies was associated with longer transplant-free survival time on adjusted analysis, however the significance varied depending on which statistical model was used (HR 0.22-0.47, p value 0.02-0.17).
  
  
  CONCLUSIONS
  The frequency of circulating autoantibodies in patients with idiopathic pulmonary fibrosis is no different compared to healthy controls, but may be associated with longer survival.
authors.affiliation: Department of Medicine at University of California, San Francisco, 505 Parnassus Avenue, Box 0111, San Francisco, CA 94143, USA. joyce.lee@ucsf.edu
authors.forename: Joyce S
authors.initials: JS
authors.lastname: Lee
authors.forename: Eunice J
authors.initials: EJ
authors.lastname: Kim
authors.forename: Kara L
authors.initials: KL
authors.lastname: Lynch
authors.forename: Brett
authors.initials: B
authors.lastname: Elicker
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Ryerson
authors.forename: Tamiko R
authors.initials: TR
authors.lastname: Katsumoto
authors.forename: Anthony K
authors.initials: AK
authors.lastname: Shum
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Wolters
authors.forename: Stefania
authors.initials: S
authors.lastname: Cerri
authors.forename: Luca
authors.initials: L
authors.lastname: Richeldi
authors.forename: Kirk D
authors.initials: KD
authors.lastname: Jones
authors.forename: Talmadge E
authors.initials: TE
authors.lastname: King
authors.forename: Harold R
authors.initials: HR
authors.lastname: Collard
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001323:Autoantibodies / Q000097:blood*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D054990:Idiopathic Pulmonary Fibrosis / Q000276:immunology* / Q000601:surgery; D053208:Kaplan-Meier Estimate; D016040:Lung Transplantation; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D011379:Prognosis
chemical_list: D001323:Autoantibodies