NEUTROPHILS ARE INVOLVED IN THE NONSPECIFIC RESISTANCE TO LISTERIOSISINDUCED BY MYCOBACTERIAL INFECTIONS

A major role has been recently ascribed to the neutrophil in the resis tance to infection by Listeria monocytogenes (L. monocytogenes). Here we evaluated whether such neutrophils played a role in the non-specifi c resistance to listeriosis that develops in hosts infected by mycobac teria. 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 peritonea l macrophages in neutrophil-depleted mice allowed us to postulate a ro le for the cooperation between neutrophils and macrophages in the kill ing of L. monocytogenes. We also found listerial proliferation in hepa tocytes of neutrophil-depleted, mycobacteria-infected mice showing tha t the neutrophils may be involved in the control of listeria infection of parenchymal cells.