IFNG and tuberculosis: By contrast, the coinhibitory molecule PD-1 is upregulated on MAIT cells in several bacterial and viral infections, including hepatitis C (213) and tuberculosis (TB) (211), and PD-1 blockade leads to enhanced IFN-γ production by MAIT cells from active TB patients in response to in vitro stimulation with live bacillus Calmette–Guérin (211).