CD29 expression on CD4+ gingival lymphocytes supports migration of activated memory T lymphocytes to diseased periodontal tissue

The cell surface phenotypes of CD4⁺ cells extracted from inflammatory periodontal disease tissues were analyzed using two- and three-color immunofluorescence and flow cytometry. Cells extracted from both adult periodontal and localized juvenile periodontitis lesions showed a depressed CD4/CD8 ratio (1.0±0.1 adult periodontitis and 1.1 ±0.1 localized juvenile periodontitis) compared with cells recovered from normal/marginal gingivitis tissue (1.8 ±0.2) or with normal peripheral blood cells (2.1 ±0.1) or periodontal disease blood cells (2.1±0.1 and 1.7±0.1 for adult periodontitis and juvenile periodontitis, respectively). The monoclonal antibodies anti-2H4 and anti-4B4 were used to identify the CD45RA and CD29 antigens respectively on CD4⁺ T cells from the periodontal disease lesions. In peripheral blood, CD29⁺ cells accounted for 66–77% of the CD4⁺ population, and CD45RA⁺ cells accounted for 22–27% of the CD4⁺ subset. No differences in expression were found between peripheral blood lymphocytes from normal subjects and from periodontal disease patients. Two-color analyses of lymphocytes from periodontal diseased tissues showed that 87–89% of the CD4⁺ population were CD29⁺ and that 70–79% of the CD4⁺ cells were CD45RA⁺. Normal tissues contained significantly fewer CD4⁺CD29⁺ cells (56±4%) and CD4⁺CD45RA⁺ cells (40±4%) on average, and few, if any double-labelled cells could be accounted for. These data implied that a significant percentage of the CD4⁺ cells from the diseased tissues were both CD29⁺ and CD45RA⁺ and that these populations are found in quite different proportions in diseased periodontal tissue than in peripheral blood or nondiseased tissue. In further analyses using three-color cytometry the mean percentage of CD4⁺CD29⁺CD45RA⁺ lymphocytes extracted from periodontal disease lesions was 43±9% of the CD4⁺ population. These results suggest that CD4⁺ T lymphocytes in periodontal disease not only demonstrate varying levels of maturity but also that the accumulation of CD4⁺ T cells within the periodontal tissues maybe a result of increased adhesion and transendothelial migration.