CELLULAR ADHESION MOLECULES ON PERIODONTAL LYMPHOCYTES

T cell induced differentiation of B cells has been shown to be depende nt on the CD2/LFA-3 and LFA-1/ICAM-1 pathways. Flow cytometric analysi s was used to examine these adhesion molecules on T and B cells extrac ted from gingival tissues before and after stimulation with the putati ve periodontopathic bacteria, Porphyromonas gingivalis and Fusobacteri um nucleatum. Adhesion molecule expression on peripheral blood cells f rom healthy adults was used as a control. Approximately 50 per cent of B cells extracted from gingival tissues expressed LFA-3 and ICAM-1 co mpared with 30 per cent positive peripheral blood B cells. Around 50 p er cent of gingival T cells expressed CD2 relative to 76 per cent posi tive peripheral blood T cells. However, 40-50 per cent of both gingiva l and peripheral blood T cells expressed LFA-1. There was no differenc e in the expression of adhesion molecules on T and B cells extracted f rom health/marginal gingivitis or adult periodontitis lesions. After s timulation of gingival cells in vitro, the per cent CD2 positive T cel ls and LFA-3 and ICAM-1 positive B cells, with a decrease in LFA-1 pos itive T cells. The results therefore demonstrated that gingival T and B cells express adhesion molecules in vivo. Stimulation of these cells with periodontopathic bacteria failed to increase expression, suggest ing not only that these cells are already activated in vivo, but also that their phenotype is consistent with cell-cell contact occurring in the gingival tissues. Whether or not this cell-cell contact is also a ntigen specific remains to be determined.