IMMUNOMODULATORY AND SUPERANTIGEN ACTIVITIES OF BACTERIA ASSOCIATED WITH ADULT PERIODONTITIS

IMMUNE DYSFUNCTIONS ARE FREQUENTLY associated with chronic inflammator y diseases. Several investigators have reported that patients with sev ere periodontitis show reduced or negligible levels of proliferative r esponses of peripheral blood and gingival lymphocytes to periodontopat hic organisms. The purpose of this study was to evaluate the influence s of products from Porphyromonas gingivalis (P. gingivalis) and Actino bacillus actinomycetemcomitans (A. actinomycetemcomitans) on lymphocyt es obtained from periodontally diseased and non-diseased individuals i n order to extend our understanding of the possible, role of such bact erial components as immune modulators. Pooled cultures of either P. gi ngivalis or A. actinomycetemcomitans were disrupted using glass beads in a bead mill to prepare whole cell homogenates. These homogenates we re then co-cultured with human peripheral blood mononuclear cells (PBM C) and known lymphocyte stimulators. Cultures were pulsed with tritiat ed thymidine, harvested, and radio label incorporation was determined. Responses to toxic shock syndrome toxin-1 (TSST-1) and pokeweed mitog en (PWM) were inhibited at high concentrations of bacterial homogenate . However, as the concentration was reduced, responses induced by PWM were restored while TSST-1 induced responses remained inhibited. Such results suggest that P. gingivalis and A. actinomycetemcomitans contai n potent immunosuppressants with differential influences on lymphocyte population. These effects on B- and T-cells are independent of period ontal disease status and appear to exert their influence through non-t oxic mechanisms. In addition, work currently underway presently indica tes that obligate oral anaerobic bacteria such as P. gingivalis produc e substances with some of the characteristics of superantigens.