IFNG and tuberculosis: One assay, the enzyme-linked immunospot (ELISpot) [T-SPOT.TB; Oxford Immunotec; Oxford, UK] enumerates IFN-gamma-secreting T cells, while the other assay measures IFN-gamma concentration in supernatant by enzyme-linked immunosorbent assay (ELISA) [QuantiFERON-TB Gold, QuantiFERON-TB Gold In-Tube; Cellestis; Carnegie, Australia].