Human T cell adhesion to endothelium stimulated by membrane components extracted from strains of Bacteroides vulgatus (member of B. fragilis group).

Bacteroides fragilis is reported to be less virulent than other Gram negative rods, existing in normal gut flora (e.g. Enterobacteriaceae). Lymphocytic infiltration, a typical finding in chronic infection, depends on cell extravasation and trafficking towards a site of antigen, a process that is regulated by endothelial expression of adhesion molecules. We have studied the ability of lipopolysaccharides and capsular polysaccharides of B. vulgatus group to induce human T cell adhesion to cultured endothelial cells. Both components of the bacterium caused markedly lesser T cell adhesion than LPS extracted from E. coli. Our data suggest that lower virulence of members of B. vulgatus group might be also dependent on its decreased ability to induce lymphocyte attachment to endothelium and subsequent tissue infiltration.