Increased Host Resistance to Infection Elicited by Lipopolysaccharides from Brucella abortus

Summary

Lipopolysaccharides isolated from cell walls of Brucella abortus 19-9R increase resistance in mice to infections with Salmonella typhimurium, Salmonella typhosa, Diplococcus pneumoniae, or Streptococcus mastitidis. In this respect, the action of Brucella LPS is similar to that of lipopolysaccharides obtained from other gram-negative bacteria. However, considerably larger amounts of Brucella LPS are required to produce protection than is the case with other lipopolysaccharides. Brucella LPS also differs from other lipopolysaccharides in not eliciting the Shwartzman reaction or epinephrine-induced dermal necrosis and in having a low pyrogenicity. Brucella LPS does not contain measurable amounts of β-hydroxymyristic acid which is always present in appreciable amounts in lipopolysaccharides from other gram-negative bacteria. The ability of Brucella LPS to increase host resistance to infection appears to be independent of prior sensitization of the host to Brucella.