• Yu-hang Ai, Yong-ming Yao, and Xin-gui Dai.
• Department of Intensive Care Unit, Xiang-Ya Hospital of Central South University, Changsha 410008, China.
• Zhonghua Wai Ke Za Zhi. 2009 Jan 1;47(1):58-61.

ObjectiveTo investigate the effect of apoptosis of CD4+ CD25+ regulatory T cells (Tregs) on proliferation as well as secretory function of effector T cells (Teff) and potential influence of Xuebijing injection on them in septic rats.MethodsA sepsis model was reproduced by cecal ligation puncture (CLP), and Wistar rats were randomly divided into the control group (n = 8), sham-operated group (n = 8), CLP group (n = 8), and Xuebijing injection treatment group (n = 8). CD4+ CD25+ Tregs in each group were separated by immunomagnetic beads isolate system on day 3, the apoptosis rate, expression of forkhead/winged helix transcription factor p3 (Foxp3) and cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) on Tregs were analyzed by flow cytometry, and secretion levels of interleukin (IL)-10 from Tregs were measured by ELISA. Following co-culture of CD4+ CD25+ Treg with CD4+ CD25- T cells (1:1) for 68 hours, proliferative activity of Teff was determined by MTT, and IL-2/sIL-2R alpha levels were measured by ELISA.ResultsThe apoptosis rate of Tregs in control group was 12.03% +/- 0.89%, which was not significantly different from sham-operated group 9.48% +/- 2.17%. The apoptosis rate of Tregs in CLP group 5.87% +/- 0.44% was lower than that in control group (P < 0.01), and treatment with Xuebijing injection markedly enhanced the apoptosis of Tregs 27.29% +/- 2.48%. Compared to CLP group, expression of Foxp3, CTLA-4, and the secretion of IL-10 of Treg were significantly lowered in Xuebijing injection group (all P < 0.01). The Teff proliferative activity in response to ConA, and IL-2 levels of Teff in CLP group were significantly suppressed compared with control group (P < 0.01), and secretion of sIL-2R alpha in the supernatants was much higher than that of the control group. In comparison to the CLP group, inhibitory rate of Teff proliferative activity and the sIL-2R alpha levels were significantly decreased, while the secretion of IL-2 was increased in Xuebijing injection group (P <0.01).ConclusionCD4+ CD25+ Tregs could markedly upregulate the suppressive function on Teff in sepsis, and treatment with Xuebijing injection effectively enhanced apoptosis of Tregs, thereby down-regulating the suppression on Teff.

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