Lrrk2^−/− mice are more susceptible to S. Typhimurium–induced peritoneal inflammation. (a) ELISA analysis of IL-1β levels in PCF and sera of littermate control (WT) and Lrrk2^−/− mice 6 h after S. Typhimurium infection. (b) Absolute number of total peritoneal cells and neutrophils (CD11b⁺ Ly6G⁺) from PCF of WT and Lrrk2^−/− mice 6 h after S. Typhimurium infection. (c) ELISA analysis of IL-1β from supernatants of an overnight-cultured equal number of neutrophil cells isolated from flushed peritoneal cells of WT and Lrrk2^−/− mice, which were infected by S. Typhimurium for 6 h. (d) Bacterial burden in blood, PCF, and spleens of WT and Lrrk2^−/− mice 24 h after S. Typhimurium infection. (e) Mice were administered with PBS or recombined mouse IL-1β (250 ng/mouse) for 4 h followed by S. Typhimurium infection for 24 h. Bacterial burden in blood, PCF, and spleens were monitored by serial dilution. (f) Survival of littermate control (WT) and Lrrk2^−/− mice infected intraperitoneally with S. Typhimurium (10² CFUs/mouse). *, P < 0.05; **, P < 0.01; ***, P < 0.001; determined by Student’s t test (a–e) or the Kaplan-Meier method (f). Data in a–e are representative of three independent experiments, and n = 5 mice/group; data in f are representative to two independent experiments, and n = 12 mice/group.