Functional analyzes of peripheral blood and locally infiltrated T cells in periodontitis patients.

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Previous studies demonstrated that CD4^+CD45^+T lymphocytes predominated in chronically inflamed periodontal lesion and the serum lgG2 titer against Porphyromonas gingivalis (P.g.) exhibited corelation with clinical index in periodontitis patients. To further examine the local and general immune responses involved in marginal periodontitis, proliferative responses of peripheral blood T lymphocytes against P.g.-derived antigens, P.g. sonicate extract (P.g.S.E.) and cytokine production in inflamed periodontal tissue was examined. The average of stimulation index (S.I.) in 25 patients was 1.63, which is higher than 0.99 obtained from healthy volunteers. Seven patients showed remarked proliferative responses to P.g.S.E.with over S.I.2. In the 5 healthy volunteers who exhibited high S.I., proliferative response to P.g.S.E.was inhibited by the addition of anti-CD4 and anti-class II MHC monoclonal antibodies. This suggested that CD4^+T cells recognized P.g.-derived antigen in class II MHC-res … More tricted manner, resulting in their proliferation. Flow cytometric analysis showed that the proportion CD45RA^+CD45RO^+ was increased among proliferating T cells by the stimulation of P.g.S.E.. To detect CD45 isoform expression in detail, RT-PCR by the primers flanking the alternatively spliced exons was introduced. The profile of amplified CD45 mRNA revealed that P.g.S.E.-stimulated T cell increased the expression of single exon form of CD45mRNA,containing 5th exon, as well as CD45RO isoform mRNA,indicating more complicated expression of CD45 isoform than that detected by flow cytometry. Gingival biopsies from periodontitis patients, where RNA was extracted to examine the expression of cytokine mRNA in inflamed periodontium by RT-PCR.T cell-derived cytokine, IL-2 and IL-4 mRNAs were not detected in RNA from gingival biopsies althogh they were successfully amplified in RNA from CD3-activated peripheral blood T cells. These results may suggest that infiltrating T cells in chronically inflamed periodontium decrease the ability to secret those cytokines and loss the regulatory functions in local immune responses. Further investigation would be necessary particulary for clarifying cytokine production by P.g.-activated T cells in inflamed gingiva. Less