IL18 and bacterial infectious disease: Interestingly, peritoneal macrophages and neutrophils have been reported as a source of IFN-γ [55–58], although this remains controversial [59]; nevertheless, it is worth noting that Schleicher et al. [59] treated peritoneal cells with IL-12, IL-18, and LPS for 72 h, which differs from our bacterial infection model (6–24 h).