α2 integrin–deficient mice display a diminished PMN response to Listeria infection. (A) Wild-type (WT) and α2 integrin–deficient (KO) mice were infected with 5 × 10⁴Listeria intraperitoneally. At indicated times after infection, the absolute peritoneal PMN number was determined. Shown is the combination of 3 experiments (mean ± SEM), with each point representing 4-8 mice. P = .046 at 6 hours after infection. (B) WT and KO mice were injected with thioglycollate intraperitoneally. At indicated times after injection, the absolute peritoneal PMN number was determined. Shown is the combination of 3 experiments (mean ± SEM), with each point representing 5-6 mice (time 0 hours, 3-4 mice). (C,D) Representative cytospin preparations of peritoneal exudates at 6 hours after Listeria infection from (C) wild-type and (D) α2 integrin–deficient mice.