T-SPOT.TB is an enzyme-linked immunospot assay, an in vitro test that measures interferon-gamma (IFN-γ) release of activated MTB-specific effector T cells isolated from patients’ blood or serous effusions within 2 days and is not cross-reactive with Bacillus Calmette-Guerin or most non-tuberculous mycobacteria11. This evidence concerns the gene IFNG and tuberculosis.