At 48 h post-infection, the supernatant of U937 macrophages infected with LRV-1+ isolates contained significantly higher concentrations of TNF-α (p < 0.01) and IL-1β (p < 0.0001), but a lower concentration of IFN-γ (p < 0.01), compared to macrophages infected with LRV-1− isolates (Figure 4, Figures S1 and S2). This evidence concerns the gene IL1B and infection.