FIG. 2.

Bacterial internalization as a function of exposure to IFN-γ. MH-S cells were seeded and grown in media (changed daily) for 7 days, with varying durations of exposure to IFN-γ (25 ng/mL/day) lasting between 0 and 6 days before inoculation with the type II Streptococcus pneumoniae D39. Bacterial internalization was measured as the number of internal bacterial CFUs released from MH-S cells after treatment with gentamicin and saponin. Bacterial internalization was quantified as bacteria internalized per macrophage and are reported here as proportions of the mean CFUs internalized in IFN-γ unexposed cells. Figure layout is as described in Figure 1 except that asterisks represent P values <0.01.