Possible Pathogenic Effect of Streptococcus mitis Superantigen on Oral Epithelial Cells

Abstract

Viridans and non-hemolytic streptococci in oral cavity have been suggested to be involved in the occurrence of some oral disorders and systemic diseases such as Behcet’s disease and Kawasaki disease. However, little is known about the pathogenic roles of extracellular products of these streptococci. Recently, we isolated a strain of Streptococcus mitis, strain 108, from the tooth surface of a male infant with aseptic meningitis and prepared two fractions, F-1 and F-2, from the concentrated culture supernatant. The fraction F-1 induced inflammatory cytokine production in human peripheral blood cell and gingival fibroblast cultures (1). The fraction F-2 had superantigenicity: it induced proliferation of human T cells bearing Vb2 and Vb5.1 T cell receptors in the presence of irradiated autologous peripheral blood mononuclear cells (2). In this study, we examined the cytotoxic effects of human peripheral blood T cells activated with the F-2 on oral epithelial cells and discussed the possibility that the superantigen were associated with the pathogenesis of oral mucosal disorders.