T-cell antigen specificity in humans following stimulation with Porphyromonas gingivalis

The effects of Porphyromonas gingivalis stimulation on T-cell clonality and cytokine mRNA expression in peripheral blood mononuclear cells from individuals with gingivitis and periodontitis were investigated. Clonality of T cells was investigated by reverse transcription-polymerase chain reaction (RT-PCR) and single-strand conformation polymorphism analysis. Cytokine mRNA expression was investigated by RT-PCR. Whereas unstimulated mononuclear cells did not demonstrate obvious clonality, clonal expansion was found in most Vbeta families after stimulation. However, there was no relation between clonal change and disease category or the presence of P. gingivalis infection. Messenger RNA for interferon-gamma and interleukin-13 was upregulated whereas interleukin-4 and -10 were downregulated following P. gingivalis stimulation. Interleukin-12p35 demonstrated no consistent pattern. This study supports the concept that P. gingivalis stimulates T cells in an antigen-specific fashion. It further suggests that peripheral blood T cells may preferentially produce interferon-gamma and interleukin-13 in response to P. gingivalis stimulation irrespective of disease or P. gingivalis status.