Interaction between Actinobacillus actinomycetemcomitans lipopolysaccharides and human hemoglobin

Actinobacillus actinomycetemcomitans, a bacterium associated with juvenile periodontitis, was found to use human hemoglobin as a source of iron for cell growth. Cultivation in the presence of hemoglobin had only a slight effect on the cellular protein pattern, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis. Lipopolysaccharides obtained from A. actinomycetemcomitans were found to have a strong capacity to bind hemoglobin. This interaction appears not to involve the lipid A portion of the molecule as no inhibition was obtained when lipopolysaccharides were pre-treated with polymyxin B. This interaction between hemoglobin and lipopolysaccharides of A. actinomycetemcomitans may facilitate iron acquisition by this bacterium.