Role of previous stimulation on the neutrophil migration protects against the lethal effect of Salmonella typhimurium

Moraes, Flávio Ruas delein Júnior, Manoel Henriqueoraes, Julieta Rodini Engrácia de

The intraperitoneal inoculation of 3.8 x 109 CFU of alive Salmonella typhimurium caused 100 per cent mortality in rats. In these animals a small number of neutrophils migrated to the peritoneal cavity. The intraperitoneal inoculation of the animals with thioglycollate (Tg, 90 mg), carrageenin (Cg, 500 m g), or killed S. typhimurium (KS, 1.9 x 109 CFU) 24 hours before challenge with alive S. typhimurium caused a significant neutrophil migration to the peritoneal cavity (determined 6 hours after challenge) and protected the animals against the lethal effect of the bacteria at a rate of 50 per cent, 83 per cent and 80 per cent, respectively. However, similar treatment of the animals with brain heart infusion broth (BHI, S. typhimurium grout medium) protected the animals by only 23 per cent. The migrating neutrophils in these animals represented less than 10 per cent of those observed with other treatments. The phagocytosis activity was not associated with the survival rate as this activity was 2 times higher in the KS group than in the Tg and Cg groups, and the survival rate in this group was similar to that observed in Cg. These results suggest that the increase of neutrophil migration to the infectious site is an important factor associated with protection of the animals against the lethal effect of the bacterial infection