Specific and nonspecific protection of mice by Pseudomonas aeruginosa lipopolysaccharides.
The role of lipopolysaccharide (LPS) in eliciting a predominant cellular or humoral protection of mice is determined by the amount administered and the immunization schedule. Three basically different experimental conditions could be characterized. Five days after immunization with 100 micrograms of LPS, a nonspecific protection was observed due to the immunomodulatory capacity of lipid A. After 14 days, the same amount of LPS results in an O-specific humoral protection. On the other hand, 0.1 micrograms of LPS lead to a specific protection within 5 days after immunization due to a synergistic action of a specific humoral response (induced by the O-side chain) and a nonspecific signal modulated by lipid A. In order to study the role of each LPS region for protection, the free side chain was conjugated to albumin, followed by complexation with lipid A. To induce a nonspecific protection 5 days after immunization, the presence of lipid A was mandatory, in either the conjugated or free form. Removal of ester-linked fatty acids from free lipid A reduced its protective and mitogenic capacities by 50, and 25%, respectively.
D000818:Animals; D000907:Antibodies, Bacterial / Q000096:biosynthesis*; D007111:Immunity, Cellular; D007114:Immunization; D007115:Immunization Schedule; D008070:Lipopolysaccharides / Q000276:immunology*; D051379:Mice; D011552:Pseudomonas Infections / Q000276:immunology*; D011550:Pseudomonas aeruginosa / Q000276:immunology*
D000907:Antibodies, Bacterial; D008070:Lipopolysaccharides