Figure 2.

H. pylori arginase inhibits NO₂⁻ production by preactivated macrophages. RAW 264.7 macrophages were stimulated with IFN-γ (100 units/ml) for 24 h. Cells were washed and H. pylori SS1 WT (open bars) or rocF∷aphA3 (solid bars) was added in medium containing 0.4 mM l-arginine at an moi of 10, 100, or 1,000. [NO₂⁻] was assessed in the supernatant after 6 h. Values are expressed as mean ± SEM of six experiments performed in duplicate. **, P < 0.01; ***, P < 0.001, for H. pylori SS1 rocF∷aphA3 compared with WT by unpaired t test.