Selective expansion of T cells in gingival lesions of patients with chronic inflammatory periodontal disease

Chronic inflammatory periodontal diseases are characterized by a cellular infiltrate and are similar in many respects to other chronic inflammatory diseases. While periodontopathic bacteria have been recognized as the principal causative agent and the immune response to these bacteria is thought to be responsible for the tissue destruction, the full aetiological spectrum is still incompletely understood. In addition to many cell types such as polymorphonuclear leucocytes and macrophages, T cells have been implicated in pathogenesis and are considered to have regulatory roles in progression of the disease. Based on our recent studies demonstrating biased expression of several Vβ families in periodontitis tissues, the aim of this study was to characterize further the T cells relevant to the disease process by reverse transcription-polymerase chain reaction-single-strand conformation polymorphism (RT-PCR-SSCP) and subsequent nucleotide sequence analysis of complementarity-determining region 3 (CDR3) of the TCR β-chain. In spite of the likely involvement of numerous bacteria, the present study has clearly shown the oligoclonality of infiltrating T cells in periodontitis lesions in contrast to low clonality of peripheral blood T cells as evidenced by the appearance of distinct bands in gingival tissue samples and smear pattern of peripheral blood on SSCP gels. These were confirmed by the DNA sequencing of the CDR3 of Vβ16 of selected samples. The analysis of deduced amino acid sequences demonstrated amino acid motifs in the CDR3 region of the periodontitis lesion-derived sequences from each patient. The results indicate that gingival tissue-infiltrating T cells recognizing a limited number of antigens or epitopes are involved in the disease process

Differential expression of costimulatory molecules in chronic inflammatory periodontal disease tissue

Although B cell activation and subsequent immunoglobulin production are the immunopathological features of chronic inflammatory periodontal disease, in situ expression of costimulatory molecules in humoral immunity has not been investigated. In the present study we examined the expression of CD40, CD40 ligand (CD40L), CD80, CD86, CD28 and cytolytic T lymphocyte-associated antigen-4 (CTLA-4) on lymphocytes immunohistochemically. Cryostat sections were prepared from the gingival tissue samples of 14 patients with moderate to advanced adult periodontitis. In vitro kinetics of the expression of CD40L and CTLA-4 by peripheral blood T cells and that of CD80 and CD86 by peripheral blood B cells were also investigated by flow cytometry. Positive percentage expression of CD40L, CD28 and CTLA-4, and CD40, CD80 and CD86 was calculated for the number of CD3+ and CD19+ cells, respectively. Flow cytometric analysis demonstrated that the expression of CD40L and CTLA-4 on T cells, and CD80 and CD86 on B cells of peripheral blood was up-regulated upon activation. While most T cells and B cells expressed CD28, and CD80 and CD86, respectively, in gingival tissues, the expression of CD40L and CTLA-4 was lower but highly variable between specimens. Furthermore, these two molecules seemed to be expressed reciprocally in the lesion. As both CD40L and CTLA-4 expression are induced transiently by stimulation, variability in the expression of the molecules may reflect immunological activities and participation in the regulation of B cell activation of the lesion