IFNG and tuberculosis: In IGRAs, immune competent cells either in the form of whole blood (as in the Quantiferon Gold In-Tube (QFT)) or purified peripheral mononuclear cells (PBMCs, as in the T-SPOT.TB test) are stimulated in-vitro with ESAT-6 and CFP-10 and the degree of immune recognition is determined by measurement of the antigen specific release of interferon-gamma (IFN-γ) [9].