In situ activated T lymphocytes in active versus stable periodontal lesions

A double labeling technique was developed to detect T cell phenotype and HLA‐DR (activation) antigens on infiltrating cells in gingival biopsy sites classified as either periodontally active (≥ mm attachment loss within past 3 months), clinically similar but stable, or healthy. Serial cryostat sections were obtained from each of the above disease category biopsies in 13 periodontal maintenance patients, and were processed with sequential Leu series (T cell subsets) avidinbiotin‐peroxidase followed by anti‐HLA‐DR indirect alkaline phosphatase labeling protocols. Labeled cells were counted in repeatable fields in the sulcular, middle and oral thirds of each section, and HLA‐DR⁺ T cells (activated) were calculated. Total HLA‐DR‐labeled cells and HLA‐DR‐positive pan‐T cells and T helper cells (T_h) were all more numerous in active specimens than in healthy sites (p<0.05), and in sulcular fields than in the oral third of the section (p<0.05). Although activated T suppressor cell (T₅) densities did not vary statistically according to tissue location, active biopsies had more cells per field than either stable or healthy specimens (p<0.05), especially in the sulcular third. A majority of pan‐T, T_s and T_h cells appeared to display activation markers in active, stable and healthy biopsies. This study supports the functional role of T lymphocytes in modulating the immune response in periodontal tissues.