title: Qualitative and quantitative results of interferon-γ release assays for monitoring the response to anti-tuberculosis treatment.
abstract: OBJECTIVE
  The usefulness of interferon-γ release assays (IGRAs) in monitoring to responses to anti-tuberculosis (TB) treatment is controversial. We compared the results of two IGRAs before and after anti-TB treatment in same patients with active TB.
  
  
  METHODS
  From a retrospective review, we selected patients with active TB who underwent repeated QuantiFERON-TB Gold (QFN-Gold, Cellestis Limited) and T-SPOT.TB (Oxford Immunotec) assays before and after anti-TB treatment with first-line drugs. Both tests were performed prior to the start of anti-TB treatment or within 1 week after the start of anti-TB treatment and after completion of treatment.
  
  
  RESULTS
  A total of 33 active TB patients were included in the study. On the QFN-Gold test, at baseline, 23 cases (70%) were early secreted antigenic target 6-kDa protein 6 (ESAT-6) or culture filtrate protein 10 (CFP-10) positive. On the T-SPOT. TB test, at baseline, 31 cases (94%) were ESAT-6 or CFP-10 positive. Most of patients remained both test-positive after anti-TB treatment. Although changes in interferon-γ release responses over time were highly variable in both tests, there was a mean decline of 27 and 24 spot-forming counts for ESAT-6 and CFP-10, respectively on the T-SPOT.TB test (p< 0.05 for all).
  
  
  CONCLUSIONS
  Although limited by the small number of patients and a short-term follow-up, there was significant decline in the quantitative result of the T-SPOT. TB test with treatment. However, both commercial IGRAs may not provide evidence regarding the cure of disease in Korea, a country where the prevalence of TB is within the intermediate range.
authors.affiliation: Department of Internal Medicine, Inje University Seoul Paik Hospital, Seoul, Korea.
authors.forename: I-Nae
authors.initials: IN
authors.lastname: Park
authors.affiliation: Division of Pulmonology and Critical Care Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Tae Sun
authors.initials: TS
authors.lastname: Shim
mesh_terms: D000328:Adult; D000995:Antitubercular Agents / Q000627:therapeutic use; D005260:Female; D006801:Humans; D059425:Interferon-gamma Release Tests / Q000379:methods* / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D056910:Republic of Korea; D012189:Retrospective Studies; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis / Q000188:drug therapy* / Q000276:immunology*
chemical_list: D000995:Antitubercular Agents
keywords: Interferon-gamma release tests; Therapeutics; Tuberculosis