Cytokine profiles of T-lymphocytes from gingival tissues with pathological pocketing

Periodontal disease is an infection in which destruction occurs at sites remote from the infection, resulting in pathological pocketing. Intervening between the infection and the destruction is a dense mononuclear inflammatory infiltrate. It has been suggested that this infiltrate might have characteristics and the destructive potential of Th1-type T lymphocytes. To ascertain the nature of the infiltrates we investigated the expression of mRNA for IL-2, IL-5, and IFN-γ by gingival mononuclear cells (GMC) from healthy (n = 8) or adult periodontitis (AP) patients (n = 25) by using cytokine-specific reverse-transcription/polymerase-chain-reaction (RT-PCR). GMC, as obtained from patients' tissues, expressed IL-2, IFN-γ, or IL-5 mRNA. Significantly higher proportions of GMC from AP patients expressed IL-2 and IFN-γ mRNA than did those from healthy subjects. IFN-γ was the most consistent cytokine message detected. In other experiments, gingival T-lymphocytes (n = 12) and CD4⁺ and CD8⁺ gingival T-lymphocytes (n = 16) were isolated from gingival tissues removed surgically from AP patients. AP gingival T-lymphocytes expressed mRNA for IL-2, IFN-γ, or IL-6 prior to stimulation. After stimulation with Con A, the cells significantly up-regulated IL-5 and IL-6 message expression. Both CD4⁺ and CD8⁺ gingival T-lymphocytes expressed IFN-γ, IL-5, and some IL-2. This cumulative cytokine profile observed in these experiments is consistent with the predominance of Th1-type cells in pathological tissues and with Th2-type cells, which can also be present, being up-regulated under appropriate stimulation. Importantly, CD4⁺ and CD8⁺ lymphocytes were shown to express T1- and T2-type cytokine message, emphasizing the potential for CD8⁺ T-lymphocytes to participate in periodontal disease pathology.