FIG. 2.

Oral antigen protects mice against systemic infection by an IFN-γ-dependent mechanism. Bacterial loads in spleens of C57BL/6 wild-type (WT), IL-4^−/−, IL-10^−/−, IFN-γ^−/−, and IL-12^−/− mice fed PBS (open bars) or 2 mg of S. enterica serovar Typhimurium sonicate (hatched bars) and challenged i.p. with 10³ CFU of S. enterica serovar Typhimurium 754 1 week later are shown. Data are representative of those from four experiments with five mice per group. Statistical significance (P values for fed versus unfed groups for each strain) is indicated above the bars. NS, not significant.