This project intends to explore the role of bacterial products, including endotoxin, in periodontal disease. Organisms and their products from dental plaque which are active in the induction of cellular immunity and/or toxic reactions will be identified by correlated immunological/immunochemical studies in animals and humans. Active fractions will be isolated and chemically characterized. BIBLIOGRAPHIC REFERENCE: David A. Johnson, John C. Dombrowski, Chen-lo H. Chen and Alois Nowotny, Endotoxin Content and Immunogenicity of Human Plaque, Abstract, Meeting International Association for Dental Research, 1976.