IFNG and infection: In the present paper, we investigated anti-PPE44 T-lymphocyte responses during human infection by evaluating the frequency of PPE44-specific interferon (IFN)-γ-secreting cells by ELISpot and flow cytometry in a small cohort of healthy subjects that had proven positive to PPD (PPD+) in vitro, in patients with active tuberculosis, in subjects vaccinated with BCG and in unvaccinated, PPD- healthy controls.