title: Apoptosis in Porphyromonas gingivalis-specific T-cell lines.
abstract: Fluorescence-activated cell sorter analysis and transmission electron microscopy were used to determine the presence of apoptotic cells in Porphyromonas gingivalis-specific T-cell lines established from the peripheral blood of 10 P. gingivalis-infected individuals. P. gingivalis outer membrane antigens were presented to the T cells by autologous Epstein-Barr virus-transformed B cells for 6, 24, 48 and 72 h. Transmission electron microscopy demonstrated the presence of typical apoptotic cells in all cultures. Annexin V-positive cells were present at low concentrations at all 4 four periods. A mean of approximately 2-3% of the CD4 cells and 1-3.5% of the CD8 cells were annexin V-positive, with an increase to around 5.5% positive CD4 cells at 6 h in wells containing P. gingivalis compared with cultures not containing antigen. This difference was not, however, significant at the 0.05 level (P = 0.073). The mean (+/- standard error) CD4:CD8 ratios of the T-cell lines when first established using peripheral blood mononuclear cells as antigen-presenting cells was significantly higher (5.2 +/- 1.1) than when transformed B cells were used as antigen-presenting cell (1.2 +/- 0.5). While this study has shown apoptosis occurring in the T-cell lines, it has not shown definitively that the reversion in the CD4:CD8 ratio in the P. gingivalis-specific T cells following antigen presentation by autologous Epstein-Barr virus-transformed B cells is due to apoptosis of a CD4 population. Alternatively, the reversion in the CD4:CD8 ratio could be due to a selective proliferation of the CD8 population which, in turn, could be relevant to the immunopathology of periodontal disease induced by P. gingivalis.
authors.affiliation: Immunopathology Laboratory, School of Dentistry, University of Queensland, Brisbane, Australia.
authors.forename: E
authors.initials: E
authors.lastname: Gemmell
authors.forename: S
authors.initials: S
authors.lastname: Prajaneh
authors.forename: D A
authors.initials: DA
authors.lastname: Grieco
authors.forename: J J
authors.initials: JJ
authors.lastname: Taylor
authors.forename: G J
authors.initials: GJ
authors.lastname: Seymour
mesh_terms: D000704:Analysis of Variance; D017304:Annexin A5; D000907:Antibodies, Bacterial / Q000097:blood; D000942:Antigens, Bacterial / Q000276:immunology; D017209:Apoptosis; D001425:Bacterial Outer Membrane Proteins / Q000276:immunology; D016516:CD4-CD8 Ratio; D002460:Cell Line; D004791:Enzyme Inhibitors; D005434:Flow Cytometry / Q000379:methods; D006801:Humans; D008854:Microscopy, Electron; D010510:Periodontal Diseases / Q000276:immunology / Q000382:microbiology*; D016966:Porphyromonas gingivalis / Q000472:pathogenicity*; D013601:T-Lymphocytes / Q000166:cytology / Q000382:microbiology*; D019014:fas Receptor / Q000276:immunology
chemical_list: D017304:Annexin A5; D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D004791:Enzyme Inhibitors; D019014:fas Receptor