IL-12 treatment decreased total cell numbers in lungs of TB-infected mice. Total numbers of CD8+, CD4+, and NK+ (CD49b/Pan-NK) cells were determined by flow cytometry of total cells obtained from lung homogenates. Squares, IL-12 treatment; circles, PBS treatment. CD8+ (A), CD4+ (B), and NK (C) cell numbers in whole lungs were reduced in IL-12-treated mice compared to saline controls. Each data point represents three to four mice and the bars represent the standard errors. CD4+ and NK+ graphs are representative of CD4−/− mice from three experiments and WT mice from four experiments; CD8+ graphs are representative of CD4−/− mice from two experiments and WT mice from three experiments. In the above experiment with CD4−/− mice, total cell numbers from whole lungs were not available for early times postinfection. *, P ≤ 0.05; **, P ≤ 0.01.