Reduced MSU-triggered peritonitis in DAPK-deficient macrophages. Decreased IL-1β production and neutrophil influx in MSU-treated Dapk^−/− mice. Phosphate-buffered saline (0.5 mL) with or without MSU crystals (1 mg) was intraperitoneally administered to control and Dapk^−/− mice. (A) Mice were killed 6 hours later, and levels of IL-1β in peritoneal lavage were determined. (B) The population of neutrophils in peritoneal lavage was assessed by staining with anti–Ly-6G and anti-CD11b. Numbers indicate percentage of polymorphonuclear neutrophils (PMN).