Fig 4. T cells and NK cells in spleens of BCG-immunized mice provoke specific IFNγ responses upon stimulation with PPD antigen.

At 6 weeks after the single vaccination of mice with BCG or PBS, splenocytes were harvested from the immunized and the control mice (n = 5 per group). The cells were cultured (2 × 10⁷ cells/mL) in the presence or absence of PPD (50 μg/mL) at 37°C for 24 h. A portion of the culture supernatants was harvested for ELISA, and then brefeldin A (10 μg/mL) was added to the remaining cell cultures. The production level of IFNγ in the culture supernatants was measured by ELISA (A). The splenocytes harvested were stained with anti-mouse CD4 (B) or anti-mouse NK1.1 (C) followed by anti-mouse IFNγ mAbs, and then analyzed with flow cytometry. The data are presented as mean ± standard deviation, and p values <0.05 were considered statistically significant. Similar results were obtained in three independent experiments. *p < 0.05; **p < 0.01; ***p < 0.0001.