FIG. 4.

Role of endogenous IL-18 and IL-12 on resolution of replicative L. pneumophila lung infection. A/J mice were administered control antibody (IgG2a), anti-IL-18R MAb, anti-IL-12 MAb, or both MAbs prior to intratracheal inoculation with L. pneumophila (10⁶ bacteria/mouse). At specific time points thereafter, mice were euthanatized, and lungs were excised and homogenized. Growth of L. pneumophila in the lung tissue was quantified by culture of lung homogenates. Mice were treated with control antibody (IgG2a) (▾), anti-IL-18R MAb (○), anti-IL-12 MAb (×), anti-IL-18R MAb and anti-IL-12 MAb (▴). Results represent means ± standard errors of the means for five animals per treatment group. Symbols for statistical significance: ∗, significantly greater than mice treated with IgG2a (P < 0.05); t, significantly greater than mice treated with anti-IL-12 MAb alone (P < 0.05); ψ, significantly greater than mice treated with anti-IL-18R MAb alone (P < 0.05).