Impaired resistance to Listeria monocytogenes in mice chronically exposed to cadmium.

It is shown in this work that resistance to Listeria monocytogenes is greatly impaired in C57BL/6 mice chronically exposed to cadmium (Cd) chloride. Animals received 0.5 mg/kg Cd by an intraperitoneal route three times a week during a 4-week period and were then infected with L. monocytogenes. Susceptibility to this pathogenic bacteria was not due to a defect of the specific immune response, since mice developed normal levels of anti-Listeria T cell-mediated immunity and did not show any impairment of macrophage activation. In fact, bacterial growth in organs was rapid in Cd-exposed mice during the early phase of infection, suggesting an impairment of non-specific defence mechanisms. Experimental data indicate that the susceptibility to L. monocytogenes might be due to a defect of macrophage recruitment in sites of infection during the early phase of the host response.