FIG. 2.
IFN-γ production by cultures of lung and spleen cells from M. tuberculosis-infected mice. (A) Lung cells from infected control (solid bars) and IL-6 KO (open bars) mice were stimulated for 5 days with live M. tuberculosis organisms, and IFN-γ secretion was analyzed by ELISA. The data are the means and standard deviations of three or four mice per group. (B) Spleen cells from infected control (solid bars), IL-6 KO (hatched bar), or IL-4 KO (cross-hatched bar) mice were stimulated for 72 h with M. tuberculosis organisms. IFN-γ secretion was then analyzed by ELISA. The data are the means and standard deviations of triplicate samples. Spleen and lung cell cultures from uninfected mice produced no detectable IFN-γ during these experiments (data not shown). An asterisk indicates a significant difference between the control and both IL-6 KO and IL-4 KO mice (P < 0.05) by the Student t test.