Influence of aluminium ions on the resistance of mice to the experimental Listeria monocytogenes infection

This study presents evaluation of effects of aluminium ions on the development of experimental infection induced by the injection of Listeria monocytogenes bacteria into growing mice. We show that single exposure of mice to 0.05 LD50 or 0.5 LD50 of aluminium ions does not affect the accumulation of bacteria in liver and spleen of experimental animals. Long-term exposure of mice to aluminium ions (injection of 0.05 LD50 Al3+ every 3 days for totally 6 weeks) did not slow down the increase in weight of animals while in the infected animals aluminium significantly reduced their growth. Animals subjected to chronic aluminium exposure have shown lower accumulation of bacteria in liver 24 h after the initiation of experimental infection as compared to the mice after single injection of 0.05 LD50 Al3+. Also, long-term exposure to aluminium causes more complicated development of experimental infection, which was evidenced by the decreased survival of aluminium-treated animals (77% compared to 83% in control group) as well as by the increase in the fraction of animals carrying infection after 6 weeks (36% versus 5% in control group). In addition, aluminium-exposed animals had significantly lower blood serum agglutination titer to the listeria, and decrease in the delayed type of hypersensitivity to the listeria antigens. Results, presented here, indicate that the long-term exposure to low aluminium doses activates the antibacterial defence in experimental animals while the specific immunity becomes suppressed