Relationship between immune response of regulatory T cells in peripheral blood and sepsis in patients with severe burns

Dong Ning; Wang Xinqi; Li Feng; Zhu Xiaomei; Zhang Qinghong; Yao Yongming

doi:10.3969/j.issn.1672-8521.2017.03.001

Abstract：Objective: To investigate the changes of immune function of regulatory T cells (Tregs) in peripheral blood of patients with severe burns, and explore its correlation with the complicated sepsis. Methods: Forty patients with burn area ≥ 30％ total body surface area (TBSA) were enrolled in present study, and divided into sepsis group (n=26) and non-sepsis group (n=14). The peripheral venous blood samples were collected on 1, 3, 7, 14, 21 and 28 days after injury to separate CD4+CD25+Tregs. The expressions of FOXP3 and CTLA-4 on the surface of CD4+CD25+Tregs were measured by flow cytometry, and the levels of mean fluorescence intensity (MFI) of interleukin-10 (IL-10) as well as transforming growth factor-β (TGF-β) in CD4+CD25+Tregs were further determined by flow cytometry after stimulation in vitro. Results: The expressive levels of FOXP3 in CD4+CD25+Treg increased significantly 7 and 14 days after injury, and of CTLA-4 markedly enhanced 14 days after injury in sepsis group than in non-sepsis group (P<0.05). The MFI of IL-10 in CD4+CD25+Tregs at the 1st day after injury was significantly higher than the health controls (P<0.01), and the IL-10 MFI level on day 21 after injury was markedly higher in sepsis group than in non-sepsis group (P<0.05). Likely, TGF-β MFI levels in CD4+CD25+Tregs on day 14 and 21 were significantly higher in sepsis group than in non-sepsis group (P<0.05). Conclusions: The immune response of Tregs shows dramatic enhancement in patients with severe burns, which further down-regulates the cell-mediated immunity by releasing immunosuppressive cytokines including IL-10 and TGF-β. Dynamic monitoring the expression and function of Tregs might be helpful for assessment of the clinical course as well as septic complications in patients following extensive burns.