title: Interferon-γ Enzyme-Linked Immunospot Assay in Patients with Tuberculosis and Healthy Adults.
abstract: BACKGROUND
  Interferon-γ assays based on tuberculosis (TB)-specific antigens have been utilized for diagnosing and ruling out latent TB and active TB, but their utility is still limited for TB incidence countries. The aim of this study is to understand the clinical utility of enzyme-linked immunospot (ELISpot) assays among patients with clinically suspected TB and healthy adults in clinical practices and community-based settings.
  
  
  METHODS
  The ELISpot assays (T SPOT.TB, Oxford Immunotec, UK) were prospectively performed in 202 patients. After excluding those with indeterminate results, 196 were included for analysis: 41 were TB patients, 93 were non-TB patients, and 62 were healthy adults.
  
  
  RESULTS
  The sensitivity and negative predictive values of the T SPOT.TB assays for the diagnosis of TB were 87.8% and 89.1%, respectively, among patients with suspected TB. The agreement between the tuberculin skin test (10-mm cutoff) and the T SPOT.TB assay was 66.1% (kappa=0.335) in all participants and 80.0% (kappa=0.412) in TB patients. Among those without TB (n=155), a past history of TB and fibrotic TB scar on chest X-rays were significant factors that yielded positive T SPOT.TB results. There was a significant difference in the magnitude of T SPOT.TB spot counts between TB patients and non-TB patients or healthy adults.
  
  
  CONCLUSIONS
  The T SPOT.TB assay appeared to be a useful test for the diagnostic exclusion of TB. A positive result, however, should be cautiously interpreted for potential positives among those without active TB in intermediate TB incidence areas.
authors: Department of Internal Medicine, Hallym University College of Medicine, Chuncheon, Korea.
authors: Cheol-Hong
authors: CH
authors: Kim
authors: Department of Internal Medicine, Hallym University College of Medicine, Chuncheon, Korea.
authors: Jong-Yeop
authors: JY
authors: Kim
authors: Department of Internal Medicine, Hallym University College of Medicine, Chuncheon, Korea.
authors: Yong Il
authors: YI
authors: Hwang
authors: Department of Internal Medicine, Hallym University College of Medicine, Chuncheon, Korea.
authors: Chang Youl
authors: CY
authors: Lee
authors: Department of Internal Medicine, Hallym University College of Medicine, Chuncheon, Korea.
authors: Jeong-Hee
authors: JH
authors: Choi
authors: Department of Internal Medicine, Hallym University College of Medicine, Chuncheon, Korea.
authors: Yong-Bum
authors: YB
authors: Park
authors: Department of Internal Medicine, Hallym University College of Medicine, Chuncheon, Korea.
authors: Seung-Hun
authors: SH
authors: Jang
authors: Department of Internal Medicine, Hallym University College of Medicine, Chuncheon, Korea.
authors: Heungjeong
authors: H
authors: Woo
authors: Department of Internal Medicine, Hallym University College of Medicine, Chuncheon, Korea.
authors: Dong-Gyu
authors: DG
authors: Kim
authors: Department of Internal Medicine, Hallym University College of Medicine, Chuncheon, Korea.
authors: Myung Goo
authors: MG
authors: Lee
authors: Department of Internal Medicine, Hallym University College of Medicine, Chuncheon, Korea.
authors: In-Gyu
authors: IG
authors: Hyun
authors: Department of Internal Medicine, Hallym University College of Medicine, Chuncheon, Korea.
authors: Ki-Suck
authors: KS
authors: Jung
authors: Department of Laboratory Medicine, Hallym University College of Medicine, Chuncheon, Korea.
authors: Hyun Soo
authors: HS
authors: Kim
keywords: Enzyme-Linked Immunospot Assay; Interferon-gamma; Tuberculosis