IFNG and tuberculosis: Such assays include the QuantiFERON–TB Gold (QFT), which utilizes Mtb-specific antigens ESAT-6, CFP-10, and TB7.7 to stimulate immune cells in a blood collection tube with IFNγ secretion measured by enzyme-linked immunosorbent assay (ELISA), and T-SPOT.TB, which uses similar antigens with IFNγ measured by ELISPOT.