RESUMO
OBJECTIVE: To investigate the changes in T helper cells (Th1 and Th2) of mesenteric lymph node (MLN) and blood Th1 and Th2 cells in septic rats. METHODS: Ninety-six male Wistar rats were randomly divided into two groups according to random number table method: sham operation group and model group. Intra-abdominal infection with sepsis was induced by cecal ligation and puncture (CLP). Eight rats in each group were sacrificed after collection of blood samples and MLN samples at 0, 6, 12, 24, 48 and 72 hours after CLP. The ratio of Th1/Th2 and the percentage of regulatory T cell (Treg) in CD4+ T cells in blood and MLN were respectively determined by flow cytometry. RESULTS: In model group, the ratio of Th1/Th2 in abdominal aorta blood increased significantly at 6 hours and reached summit at 12 hours, then it decreased persistently, and when compared with sham group, the ratio of Th1/Th2 was significantly higher at 6, 12, 24 hours (0.82±0.15 vs. 0.60±0.22, 1.23±0.44 vs. 0.76±0.31, 0.85±0.25 vs. 0.66±0.32) and lower at 72 hours (0.41±0.16 vs. 0.59±0.13, P<0.05 or P<0.01). The ratio of Th1/Th2 in MLN of model group reached summit at 6 hours, then decreased significantly, and when compared with sham group, the ratio of Th1/Th2 was significantly higher at 6 hours (1.01±0.16 vs. 0.52±0.13) and lower at 12, 24, 48 and 72 hours (0.34±0.11 vs. 0.53±0.09, 0.23±0.08 vs. 0.51±0.09, 0.17±0.07 vs. 0.47±0.15, 0.16±0.06 vs. 0.53±0.11, P<0.05 or P<0.01). Compared with sham group, the percentage of Treg in MLN of model group was increased at 12, 24, 48 and 72 hours after CLP (9.62±0.69 vs. 7.65±0.67, 9.84±0.74 vs. 8.08±1.06, 10.95±2.09 vs. 7.83±1.15, 10.81±1.34 vs. 8.35±1.12, P<0.05 or P<0.01). There was a negative correlation between the ratio of Th1/Th2 and the percentage of Treg in MLN (r=-0.882, P<0.05). CONCLUSION: Cellular immune function of MLN is suppressed during severe intra-abdominal infection, which induces translocation of gut-derived endotoxin to mesenteric lymphatics, resulting in corporal immuno-suppression, with manifestation of Th1/Th2 cell shift. Immuno-suppression of MLN is related to a higher percentage of Treg due to the effect of endotoxin.
