Neutrophils are involved in the non-specific resistance to listeriosis induced by mycobacterial infections.

A major role has been recently ascribed to the neutrophil in the resistance to infection by Listeria monocytogenes (L. monocytogenes). Here we evaluated whether such neutrophils played a role in the non-specific resistance to listeriosis that develops in hosts infected by mycobacteria. We found that the depletion of neutrophils completely abrogated the resistance conferred by the activated macrophages induced during the mycobacterial infection. The lack of killing by activated Kupffer cells and the visualization of bacteria proliferating inside peritoneal macrophages in neutrophil-depleted mice allowed us to postulate a role for the cooperation between neutrophils and macrophages in the killing of L. monocytogenes. We also found listerial proliferation in hepatocytes of neutrophil-depleted, mycobacteria-infected mice showing that the neutrophils may be involved in the control of listeria infection of parenchymal cells.