Immunohistochemical characterization of lymphocyte subsets in chronic adult periodontitis

It is well known that interactions between microbial dental plaque and the host immune system play a major role in the etiopathogenesis of periodontal disease. The aim of the present study was to analyze the phenotypic properties of gingival T lymphocytes and subsets in patients with chronic inflammatory adult periodontitis (AP) showing various degrees of inflammation and to relate the results to the immunopathogenesis of AP. Gingival biopsies were obtained from patients aged between 26 and 52 yr who were grouped according to gingival index scores (GI) of 1, 2, and 3. Using immunohistochemical techniques, T cells (CD2+), T-helper cells (CD4+) and T-suppressor cells (CD8+) were identified in three well-defined areas of the biopsy samples. Moreover, peripheral blood was collected from the same patients, and relative counts of B cells (CD19+), HLA-DR+ cells and IL-2R+ cells as well as CD3+, CD4+, CD8+ cells were determined using three color flow cytometry. While the blood results were found to be within the normal ranges, the relative counts of CD4+ cells showed statistically significant decreases as the GI score increased. Similarly, the CD4+/CD8+ ratio also decreased. Moreover, gingival T lymphocyte and subset counts appeared to be related to the severity of gingival inflammation. Particularly, CD4+ cells showed a significant increase with the GI score. Furthermore, the CD4+/CD8+ ratio beneath the pocket epithelium was apparently correlated with increasing GI score (p < 0.05). The cytotoxic effect of CD8+ cells seems to be more prominent at the local level while the suppressor effect is more active systematically. This means that the price of systemic protection appears to be local destruction.