Variation in immune state of mesenteric lymph node induced by intra-abdominal infection in sepsis rats

Abstract

Objective To investigate the variation in the immune state of mesenteric lymph node (MLN) during intra-abdominal infection in sepsis rats. Methods Ninety-six male Wistar rats weighing 200-250 g were randomly divided into 2 groups (n = 48 each): sham operation group and intra-abdominal infection group. Intra-abdominal infection was induced by cecum ligation and puncture (CLP). Eight rats in each group were killed after collection of blood and MLN samples at 0 (T_0), 6 (T_1), 12 (T_2), 24 (T_3),48 (T_4) and 72 h (T_5) after CLP. Plasma concentrations of endotoxin were detected. The ratio of T helper cells 1/T helper cells 2 (Th1/Th2) and the percentage of regulatory T cells (Treg) in CD4~+ T cells in MLN were determined by flow cytometry. Results The levels of endotoxin were significantly higher at T_2, T_3, T_4 and T_5 in group CLP than in sham operation group. The ratios of Th1/Th2 were significantly higher at T_1 and lower at T_2,T_3,T_4 and T_5 in group CLP than in sham operation group, while the percentage of Treg in CD4~+ T cells was significantly lower at T_1 and higher at T_2, T_3, T_4 and T_5 in group CLP than in sham operation group. There was a negative correlation between the ratio of Th1/Th2 and the percentage of Treg (r=-0.87, P<0.05). Conclusion Cellular immune function of MLN is suppressed during intra-abdominal infection by increasing the percentage of Treg in MLN. Key words: Sepsis; Immunity; cellular; Mesentery; T-lymphocytes; regulatory