title: Interferon-inducible protein-10 as a marker to detect latent and active tuberculosis in rheumatoid arthritis.
abstract: METHODS
  effective tuberculosis (TB) screening should be performed before anti-tumour necrosis factor alpha (TNF-α) treatment in rheumatoid arthritis (RA). The usefulness of the tuberculin skin test (TST) and QuantiFERON®-TB Gold (QFT-G) for detecting latent tuberculosis infection (LTBI) is limited.
  
  
  OBJECTIVE
  we tested the diagnostic performance of interferon-gamma (IFN-γ) inducible protein 10 (IP-10) and IFN-γ for detecting LTBI in RA patients receiving anti-TNF-α treatment.
  
  
  METHODS
  IP-10 levels were determined by enzyme-linked immunosorbent assay in 56 RA patients and 18 active TB patients. TST was performed using the Mantoux method and QFT-G was performed by measuring IFN-γ levels in whole blood treated with TB-specific antigens.
  
  
  RESULTS
  twenty-four (42.9%) TST-positive patients were defined as having LTBI. Significantly higher levels of baseline, early secretory antigenic target 6 (ESAT-6) and culture filtrate protein 10 (CFP-10) stimulated IP-10 were observed in active TB patients (median 209.9 pg/ml, 899.0 pg/ml and 880.2 pg/ml, respectively) and RA patients with LTBI (165.3 pg/ml, 904.4 pg/ml and 747.5 pg/ml, respectively), compared to those without LTBI (89.3 pg/ml, 579.4 pg/ml and 515.0 pg/ml, respectively). Baseline IP-10 has high sensitivity (83.3% and 100%) and medium specificity (67.9% and 59.6%), while ESAT-6-stimulated IP-10 has high sensitivity (87.5% and 100%) and specificity (85.7% and 71.2%) for detecting LTBI and TB. The performance of IP-10 is superior to IFN-γ for detecting LTBI (TST+) and active TB.
  
  
  CONCLUSIONS
  IP-10 may be used for detecting LTBI and as a potential biomarker to identify active TB in RA patients receiving anti-TNF-α treatment.
authors.affiliation: National Yang-Ming University, Taipei, Taiwan.
authors.forename: D-Y
authors.initials: DY
authors.lastname: Chen
authors.forename: G-H
authors.initials: GH
authors.lastname: Shen
authors.forename: Y-M
authors.initials: YM
authors.lastname: Chen
authors.forename: H-H
authors.initials: HH
authors.lastname: Chen
authors.forename: C-C
authors.initials: CC
authors.lastname: Lin
authors.forename: C-W
authors.initials: CW
authors.lastname: Hsieh
authors.forename: J-L
authors.initials: JL
authors.lastname: Lan
mesh_terms: D000328:Adult; D000368:Aged; D000942:Antigens, Bacterial / Q000276:immunology; D018501:Antirheumatic Agents / Q000627:therapeutic use*; D001172:Arthritis, Rheumatoid / Q000188:drug therapy* / Q000276:immunology; D001426:Bacterial Proteins / Q000276:immunology; D015415:Biomarkers / Q000097:blood; D054357:Chemokine CXCL10 / Q000097:blood*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007371:Interferon-gamma / Q000097:blood; D007700:Kinetics; D055985:Latent Tuberculosis / Q000175:diagnosis* / Q000276:immunology; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000276:immunology*; D011237:Predictive Value of Tests; D012372:ROC Curve; D011933:Reagent Kits, Diagnostic; D012680:Sensitivity and Specificity; D013624:Taiwan; D014374:Tuberculin Test; D014376:Tuberculosis / Q000175:diagnosis* / Q000276:immunology; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors*
chemical_list: D000942:Antigens, Bacterial; D018501:Antirheumatic Agents; D001426:Bacterial Proteins; D015415:Biomarkers; C117940:CFP-10 protein, Mycobacterium tuberculosis; C114753:CXCL10 protein, human; D054357:Chemokine CXCL10; C093276:ESAT-6 protein, Mycobacterium tuberculosis; D011933:Reagent Kits, Diagnostic; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma