LPS from Actinobacillus actinomycetemcomitans and the expression of β2 integrins and L‐selectin in an ex vivo human whole blood system

Actinobacillus actinomycetemcomitans is assumed to be an important etiological agent in localized juvenile periodontitis (LJP) and to have the ability to invade periodontal tissues. This bacterium has also been noted for its potential to cause serious extraoral infections. In this study, the effect of lipopolysaccharides (LPS) extracted from A. actinomycetemcomitans on the expression of the leukocyte adhesion molecules CD11a/CD18, CD11b/CD18, CD11c/CD18 and L-selectin (CD 62L) were measured in an ex vivo whole blood system by use of fluorescent antibodies followed by flow cytometry. LPS from Escherichia coli, which is known to elicit a strong inflammatory response was used as a reference. The expression of the beta2 integrins CD11a/CD18, CD11b/CD18, and CD11c/CD18 were significantly upregulated in granulocytes and monocytes. This expression was dose-dependent. The baseline levels of L-selectin was high on all three types of leukocytes, but on granulocytes and monocytes it decreased dramatically after stimulation with LPS. The LPS from A. actinomycetemcomitans was equally potent as LPS from E. coli in its ability to affect the expression of the leukocyte integrins and L-selectin.