RESUMO
BACKGROUND:Regulatory T cels (Treg) are classified into two subsets, nature Treg (nTreg) and induced Treg (iTreg). Although there is consensus that CD4+CD25+FoxP3+CD127-is the widely accepted phenotype of Treg, it remains unclear what is the difference in phenotypes including cytokine patterns of nTreg and iTreg. OBJECTIVE:To understand and compare the plasticity of nTreg and iTreg and to search the exact mechanism of cytokine secretion in Tregs. METHODS: We investigated the frequency and cytokine pattern of CD4+CD25+FoxP3+CD127-nTreg in freshly separated peripheral blood mononuclear cels of five healthy individuals using 8-color fluorescence flow cytometry (FACSCanto II). Subsequently, after 9 days of alostimulation in mixed lymphocytes, the frequency and cytokine pattern of CD4+CD25+FoxP3+CD127-iTreg were determined and analyzed. RESULTS AND CONCLUSION:In fresh cels, (1.5±0.70)% of CD4+ T cels were CD4+CD25+FoxP3+CD127- nTregs. Almost al these cels expressed interferon (IFN)-γ-, interleukin (IL)-2- or transforming growth factor-β+, and partial cels expressed IL-10+ or IL-10-. After 9-day alostimulation, the number of CD4+CD25+FoxP3+CD127- iTreg expressing IFN-γ+, IL-2-, IL-2+, IL-10+ or TGF-β+increased strongly. The main subsets of human nTregs were CD4+CD25+FoxP3+CD127-IFN-γ-IL-2-IL-10+TGF-β+and CD4+CD25+FoxP3+CD127-IFN-γ-IL-2-IL-10-TGF-β+ T cels. The proportion of each subset in CD4+ T cels was (1.1±0.59)% and (0.39±0.16)%, respectively. Whereas the main subsets of human iTregs were CD4+CD25+FoxP3+CD127-IFN-γ+IL-2-IL-10+TGF-β+ and CD4+CD25+FoxP3+CD127-IFN-γ+IL-2+IL-10+TGF-β+. Human nTregs were characterized as IFN-γ-IL-2- double negative, producing IL-10 and TGF-β or only TGF-β without IL-10, and not proliferatingin vitro. During the alostimulation in mixed lymphocytes, IFN-γ+ iTregs proliferated remarkably. One-third of IFN-γ+ iTreg expressed IL-2+, and two-thirds of IFN-γ+ iTregs expressed IL-2, both of which produce IL-2 and TGF-β. Our results imply that CD4+CD25+FoxP3+CD127- Treg are potentialy immunosuppressive probably because of their mandatory TGF-β and optional IL-10 production.