T-lymphocyte and cytokine expression in human inflammatory periapical lesions.

Introduction: Lymphocytes, among many cells, express different sets of cytokines, chemokines, and receptors, which are considered important mediators of periapical immune response to infection.

Methods: The aim of this study was to evaluate the mRNA expression of CD4(+)CD28(+) and CD8(+) T genes and the gene expression of interferon-γ, tumor necrosis factor-α, interleukin (IL)-1β, IL-17A, IL-10, CCL2/MCP-1, CCL4, CCL5, CXCR4, CCR5, and receptor activator for nuclear factor kappa B ligand (RANKL) in periapical interstitial fluid from human root canal infections. The samples were collected immediately after root canal cleaning and 7 days later (restrained root canal bacterial load) to characterize those gene expressions.

Results: Real-time polymerase chain reaction demonstrated significantly higher levels of CD4(+)CD28(+) and CD8(+) T-cell markers in the former root canal condition and an increase of IL-10 and CXCR4, followed by a decrease of proinflammatory cytokines such as RANKL, interferon-γ, IL-1β, and CCL5.

Conclusions: Analyses of T-lymphocyte and cytokine expression in periapical area were able to show that distinct root canal conditions might play regulatory roles in controlling local immune/inflammatory processes.