Infection of athymic mice with M. tuberculosis following transfer of splenocytes from control BALB/c and IFN-γ knockout (IFN-γ −VE) BALB/c mice. (A and B) Results for the lungs and spleen, respectively. The experimental design was identical to that for Fig. 2. Mice received either no cells, total spleen cells from wild-type BALB/c mice, CD8 cells from BALB/c mice, total spleen cells from IFN-γ knockout mice, or CD8 cells from IFN-γ knockout mice. Mice which received cells from control BALB/c mice (total spleen or CD8 cells) showed significantly reduced CFU counts compared to naive athymic mice (P < 0.05); there were no significant differences between values for naive athymic mice and mice which received either total spleen cells or CD8 cells from IFN-γ knockout BALB/c mice.