Interferon-gamma assays for the diagnosis of tuberculosis infection before using tumour necrosis factor-alpha blockers

Int J Tuberc Lung Dis. 2007 Nov;11(11):1177-82.


Objectives: Patients who receive tumour necrosis factor-alpha (TNF-alpha) blockers are mostly immunosuppressed. A study was performed to investigate whether an interferon-gamma (IFN-gamma) assay could represent an alternative approach to the tuberculin skin test (TST) for the diagnosis of latent tuberculosis infection (LTBI) in these patients.

Design: We prospectively enrolled 106 individuals into the study in two groups. Group 1 consisted of 38 healthy individuals and Group 2 included 68 patients with chronic inflammatory diseases evaluated for LTBI before the use of TNF-alpha blockers.

Results: Of all participants, nine had indeterminate IFN-gamma test results. Agreement between the two tests was poor in both groups (kappa values respectively -0.54 and 0.18). In a total of 97 subjects, 10 (10.3%) were positive by the IFN-gamma test and 49 (50.5%) by TST.

Conclusion: We found poor agreement between TST and the IFN-gamma test in our study. Our limited preliminary data should be accepted as a basis for designing future studies that will be helpful for physicians to decide whether the IFN-gamma test is more sensitive than the TST test in detecting LTBI before the use of TNF-alpha blockers.

MeSH terms

  • Adult
  • BCG Vaccine
  • Enzyme-Linked Immunosorbent Assay*
  • Female
  • Humans
  • Immunocompromised Host
  • Interferon-gamma / metabolism*
  • Male
  • Tuberculin Test
  • Tuberculosis / diagnosis*
  • Tuberculosis / metabolism
  • Tumor Necrosis Factor-alpha / antagonists & inhibitors*


  • BCG Vaccine
  • Tumor Necrosis Factor-alpha
  • Interferon-gamma