Editorial Commentary:Interferon‐γ Release Assays: What Is Their Role in the Diagnosis of Active Tuberculosis?

Abstract

Until recently, the only tool available to detect latent tuberculosis infection (LTBI) was the tuberculin skin test (TST). Although the TST has proven to be useful in clinical practice, it has known limitations [1]. An important advance in recent years has been the development of in vitro T cell—based IFN-γ release assays (IGRAs). These assays use antigens more specific to Mycobacterium tuberculosis than the PPD used in the TST. As reviewed elsewhere [2, 3], there is now considerable evidence that prior bacille Calmette-Guárin vaccination does not affect IGRA results, meaning that IGRAs have higher specificity than does the TST. Besides the high specificity, other potential advantages of IGRAs include logistical convenience, avoidance of subjective measurements (such as skin induration), need for fewer patient visits, and the ability to perform serial testing without inducing the boosting phenomenon.