Cell-mediated resistance to infection with Listeria monocytogenes in nude mice

Abstract

Congenitally athymic nude (nu/nu) NMRI mice showed increased resistance to viable L. monocytogenes cells during the initial phase of infection as compared with euthymic control mice. The i.v. LD50, as determined for euthymic mice after an observation time of 7 and 14 days, amounted consistently to 6 .times. 104 Listeria. The corresponding values determined in nude mice were increased by either 20-fold (1.2 .times. 106 Listeria after an observation time of 7 days) or 4-fold (2.4 .times. 105 Listeria after an observation time of 14 days). The transfer of spleen cells from immune euthymic donor mice into chronically infected nude mice caused almost complete elimination of Listeria within 1 wk. The injection of dextran sulfate 24 h before a secondary infection with L. monocytogenes caused loss of antibacterial resistance in chronically infected nude mice and Listeria-immune euthymic mice, this being expressed by a rapid increase in the numbers of bacteria in the spleens and the occurrence of serious signs of illness.