Impaired mobilization of STAT3-deficient neutrophils during Listeria monocytogenes infection. WT or STAT3-deficient (KO) mice were infected with L monocytogenes by intravenous injection, as described in “Methods.” (A) At 12 hours after infection, circulating neutrophil numbers in peripheral blood were determined by automated counting. Data shown are average fold change in peripheral neutrophil numbers in infected versus uninfected animals (n = 5 for WT, n = 4 for KO). (B) Spleens and livers were isolated 12 hours after infection with L monocytogenes, homogenized, and cultured. CFUs were enumerated 24 hours after culture. Shown are mean CFU/organ (n = 6 for WT, n = 4 for KO). Error bars represent SEM *P < .05.