NEUTROPHILS AND TUMOR-NECROSIS-FACTOR-ALPHA ARE IMPORTANT FOR CONTROLLING EARLY GASTROINTESTINAL STAGES OF EXPERIMENTAL MURINE LISTERIOSIS

The present study examined the need for neutrophils and tumour necrosi s factor-alpha (TNF alpha) for early defence against gut infection wit h the enteroinvasive, facultative intracellular bacterial pathogen, Li steria monocytogenes. Mice were treated with a neutrophil-depleting mo noclonal antibody (MAb) or a MAb directed against TNF alpha, and the c onsequences of these treatments on the course of orally initiated infe ction with the pathogen were monitored, By day 3, orally initiated L. monocytogenes infection in mice treated with either MAb was severely e xacerbated to the extent that up to 5000-fold more listeriae were reco vered from the walls of the stomach, small intestine, caecum or large intestine of treated mice than from controls. Systemic infection resul ting from the ingestion of L. monocytogenes was also severely enhanced in mice treated with these MAbs. Therefore, the results showed that n eutrophils and TNF alpha have a critical role in the early defence aga inst enteroinvasive L. monocytogenes infection initiated by a natural (in this case the oral) route, as well as in the control of subsequent systemic infection.