Interferon-gamma Release Assays for the Diagnosis of Latent Tuberculosis Infection: an Updated Review

Interferon-gamma (IFN-gamma) release assays (IGRAs) are in vitro immune tests that have recently been introduced as an alternative to the tuberculin skin test (TST). An increasing body of evidence supports the use of IGRAs for the diagnosis of latent tuberculosis infection (LTBI) in various clinical situations. Currently, two commercial IGRAs are available: the QuantiFERON-TB Gold In-Tube test (QFT-GIT, Cellestis Ltd, Carnegie, Australia) and the T-SPOT TB assay (T-SPOT, Oxford Immunotec Ltd., Abingdon, UK). Though the clinical performances of these two IGRAs varied widely according to the characteristics of each study, they were reported to be better than those of TST in most cases. In this concise review, the performance characteristics, the use in special clinical situations, and the guidelines of IGRAs are presented.