Influence of periodontal bacteria and disease status on V beta expression in T cells

Some bacterial antigens such as S. aureus enterotoxins can selectively stimulate T cells that express specific V beta genes of the T cell antigen receptor (TCR). The purpose of this study was to investigate whether or not periodontal bacteria could similarly alter the expression of V beta families within the TCR complex. Peripheral blood mononuclear cells (PBMNCs) were isolated from 12 patients with early onset periodontitis and 11 periodontally-healthy controls. PBMNCs were incubated in media alone, or co-cultured for 48 h with heat-inactivated A. actinomycetemcomitans, P. gingivalis and P. intermedia. Expression of five V beta families (V alpha beta 2, V beta 5, V beta 6, V beta 8, and V beta 12) was determined by use of monoclonal antibodies. Mean unstimulated expression of V alpha beta 2 and V beta 8 was significantly higher (p < 0.05) in patients than healthy controls. Co-culture with the three bacteria resulted in significant changes (increases or decreases) in V beta expression in 27% of the trials. There were no significant differences in the number or direction of changes in samples from patients and controls. When compared to unstimulated controls, 18 significant increases but no decreases in the percentage of cell expressing V alpha beta 2, V beta 5 or V beta 6 were noted following co-culture with P. intermedia. Overall, co-culture with P. intermedia significantly (p < 0.05) up-regulated expression of the five V beta families studied. These data suggest that periodontal bacteria may alter V beta expression within the T cell receptor complex.