Influence of anti–IFN-γ antibody on the Mac1⁺-mediated suppressor activity and nitrite production in culture supernatant. Suppressor assays (as in Figure 5) were performed in the presence of anti–IFN-γ antibody (20 μg/mL) or irrelevant control IgG2a (20 μg/mL). (A) Effect of anti–IFN-γ on proliferation; results are expressed as percent suppression of proliferative activity that was detected in the absence of additional cell populations. (B) Effect of anti–IFN-γ on nitrite production in MLR culture supernatant. Bars represent means ± SEs of 8 individual animals tested in 2 independent identically designed experiments. (^*P < .05 for comparison between groups, as tested by Kruskal-Wallis multiple comparison Z-test).