RESEARCH REPORTS Clinical

AbSTRACT CD4+CD25hiFoxp3+ regulatory T-cells (Tregs) are of crucial importance in regulating the immune response, including the control of any defense against infection. Their presence in periapical lesions has not been demonstrated, as yet. We hypothe-sized that Tregs infiltrate periapical lesions, where they inhibit T-cell proliferation. The aim of this study was to characterize Tregs in periapical lesions by confocal microscopy, flow cytometry, and func-tional assays. We showed that CD4+CD25hiFoxp3+ cells in periapical lesions expressed IL-10 and TGF-β. Their frequency was significantly higher than in peripheral blood and correlated with the levels of TGF-β and IL-10 in culture supernatants of periapical lesion mononuclear cells. Tregs inhibited the proliferation of responder T-cells in vitro, at least in part, by stimulating the produc-tion of IL-10. These findings suggest that CD4+CD25hi Foxp3+ cells in periapical lesions may play regulatory roles in controlling local immune/ inflammatory processes. KEy wORdS: regulatory T-cell, periapical lesion, immune response, flow cytometry, confocal microscopy, cell culture, cytokine