Fig. 1 IFN-production by pulmonary TB, TST+ and TST− individuals according to  IFNG  + 874 genotype. (A) Non-stimulated IFN-γ production (NIL); (B) PHA-stimulated IFN-γ production as measured in the supernatant (PHA); (C) Mycobacterial antigen-stimulated IFN-γ production (Ag); (D) Difference in units (ΔUI/mL) between mycobacterial antigen-stimulated and unstimulated IFN-γ production.