Differing Contribution of Polymorphonuclear Cells and Macrophages to Protection of Mice against Listeria monocytogenes and Pseudomonas aeruginosa

Abstract

Bacterial growth and lethality of L. monocytogenes in mice were augmented by carrageenan-treatment and X-irradiation (8 J kg-1), whereas growth and lethality of P. aeruginosa were augmented by X-irradiation but not by carrageenan-treatment. Protection against L. monocytogenes, at least in the early phases, appears to depend mainly on macrophages, since carrageenan depletes macrophages but not polymorphonuclear cells (PMN), whereas protection against P. aeruginosa appears to depend mainly on PMN. Ineffectiveness of PMN in elimination of L. monocytogenes is supported by histological examination and observation of intracellular killing in vitro.