Surprisingly, local macrophage infiltration and overall Arginase-1 expression did not significantly differ in infected MIF−/− mice (Figure 6A), and although the intensity of Arginase-1 staining in gene-deficient tissues was marginally weaker at day 4 of infection (Figure 6B), by day 6 it was as ubiquitous as in the wild-type controls (Figure 6C). The gene discussed is MIF; the disease is infection.