IFN-γ release assays in the diagnosis of latent tuberculosis infection among immunocompromised adults.

Immunocompromised persons with latent tuberculosis infection (LTBI) are at increased risk for tuberculosis reactivation compared with the general population. The tuberculin skin test, the traditional assay for diagnosing LTBI, has reduced accuracy in immunocompromised patients. IFN-γ release assays (IGRAs) are in vitro blood tests that measure T-cell release of IFN-γ after stimulation with antigens unique to Mycobacterium tuberculosis. Here we review the data for the use of QuantiFERON-TB Gold In-Tube and T-SPOT.TB, the two currently available IGRAs, in immunocompromised adults, including persons infected with HIV, patients with immune-mediated inflammatory disorders, candidates for treatment with tumor necrosis factor-α inhibitors, patients receiving hemodialysis, solid-organ transplant recipients, and patients with cancer. On the basis of the available data, IGRAs have advantages over the tuberculin skin test in specific patient populations and in certain situations. Further studies are needed to more accurately define the usefulness of IGRAs in immunocompromised patients.