The inflammatory response to Listeria infection is both mast cell– and α2β1 integrin–dependent. (A-C) WBB6F1-+/+ mast cell–sufficient (+/+) and WBB6F1-W/W^v mast cell–deficient (W/W^v) mice were infected with 5 × 10⁴Listeria intraperitoneally. At indicated times after infection, the percentage of PMN, the absolute PMN number, and the IL-6 concentration in peritoneal fluid were determined. Shown is the combination of 2 experiments (mean ± SEM), with each point representing 5-6 mice (time 0 hours, 2 mice). (D-F) Wild-type (WT) and α2 integrin–deficient (KO) mice were infected with 5 × 10⁴Listeria intraperitoneally. At indicated times after infection, the percentage of PMN, the absolute PMN number, and the IL-6 concentration in peritoneal fluid were determined. Shown is the combination of 2 experiments (mean ± SEM), with each point representing 4-5 mice (time 0 hours, 2 mice).