IFNG and tuberculosis: There are two commercially available assays: the Quantiferon 3G In Tube (QFT-IT) assay (Cellestis, Carnegie, Australia), which utilises an ELISA technique to measure the amount of interferon gamma secreted in response to ESAT-6, CFP-10 and TB 7.7; and the T.SPOT-TB (Oxford Immunotec, Abingdon, UK), which uses an ELISPOT to quantify the number of cells producing interferon gamma in response to ESAT-6 and CFP-10.