It is proposed to study cell detachment mediated by cellular and bacterial products found in the gingival sulcus using an in vitro assay and relating these findings to detachment of cells from each other and tooth surfaces in the pathogenesis of periodontal disease. The assay consists of incubating adherent cells with a test agent and determining the percent of detachment in comparison with controls after application of a known and reproducible shearing force. Cell supernatants from stimulated lymphocytes, lysates of polymorphonuclear leukocytes and dental plaque have been shown to enhance cell detachment. Further studies will characterize the components that produce cell detachment in cell supernatants following separation by ion exchange and gel chromatography. Established lymphoid cell lines will be assayed for ability to detach cells in the hope to be used as prototypes for detachment-enhancing activity seen with normal stimulated mononuclear cells. The mechanisms for cell detachment will be investigated. Cell detachment by plaque will be related to the degree of disease severity in the individual from whom the plaque was obtained.