IFN-γ-release assays in the management of tuberculosis

Abstract

New blood tests for TB are now available. One measures the release of IFN-γ and the other estimates the number of cells secreting IFN-γ after stimulation with antigens from Mycobacterium tuberculosis. The choice of antigens (esat-6 and cfp-10) is intended to distinguish TB infection from Bacille Calmette–Guerin vaccination. Tests differ in lymphocyte numbers, the use of an additional antigen (TB7.7 – Rv2654) and sensitivity in concurrent HIV infection. Their role in the routine diagnosis of TB is limited. In latent TB infection, the new tests correlate better with exposure to TB. However, the time course of the immune response, the significance of negative tests, conversions from positive to negative and vice versa and their value in predicting who will develop TB are not yet known. Prospective studies of these tests are needed to establish their practical value rather than theoretical role in latent TB infection. Cohorts of both immunocompetent and immunosuppressed subjects who may develop active disease should be examined.

Keywords::

• BCG vaccination
• cfp-10
• esat-6
• HIV
• IFN-γ
• latent tuberculosis infection
• tuberculin
• tuberculosis

Financial & competing interests disclosure

The author has no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

No writing assistance was utilized in the production of this manuscript.