The specific M. tuberculosis antigens are early secretory antigenic target-6 (ESAT-6), culture filtrate protein 10 (CFP-10) and TB 7.7, which are present in all M. tuberculosis and are able to stimulate the measurable release of IFN-γ in most infected persons, but are absent from bacillus Calmette-Guérin (BCG) vaccine strains and most nontuberculous mycobacteria.13 In 2008, QFT-GIT became the second IGRA approved by the US Food and Drug Administration (FDA) as a tool for diagnosing M. tuberculosis infection. Here, IFNG is linked to tuberculosis.