Activation of human B-lymphocytes by Prevotella intermedia

Black pigmented Gram negative Prevotella intermedia is a potential pathogenic bacterium in periodontal disease. Lipopolysaccharides (LPS) from Gram negative bacteria are the main antigens that stimulate antibody production and cytokine synthesis. Many reports indicate a strong correlation of specific antibodies of the immunoglobulin G (IgG) class with antigens of periopathogenic bacteria in periodontal disease. The aim of this study was to measure lymphocyte proliferation and immunoglobulin (IgA, IgG and IgM) production from B-lymphocytes in response to P. intermedia stimulation. P. intermedia was originally isolated from human periodontal pockets by means of a gingival crevice lavage method. The periodontal pocket was washed with salt solution and the solution was then aspirated into a cannula for further culturing in the laboratory. The identification of P. intermedia was made on Brucella agar. Lymphocytes were isolated from human peripheral blood. P. intermedia was added to the lymphocytes in concentrations from 0.005% to 0.1%. The immunoglobulin production was measured by enzyme-linked immunosorbent assay (ELISA). The results showed that IgA and IgG were produced in response to stimulation with P. intermedia. The IgG response was dose-dependent. No stimulation of IgM production was obtained. It is concluded from the present observations that P. intermedia can stimulate proliferation of lymphocytes and production of IgA and IgG.