[Study on apoptosis of splenic lymphocytes in rats with sepsis]

To observe the change in number of spleen T lymphocytes and B lymphocytes and apoptosis of splenocytes in rats with sepsis, and explore the mechanism of immune imbalance in sepsis.

Eighty healthy male Wistar rats were randomly divided into two groups: sham operation (n=30) and sepsis model (n=50). Sepsis model was reproduced by cecal ligation and puncture (CLP). The rats were sacrificed and their spleens were obtained at 6, 12, 24, 48, 96 hours after the model was reproduced. The pathological changes in spleen were observed by optical microscopy. Immunohistochemistry method was used to examine the positive expression of CD4(+)/CD8(+)T lymphocyte and B lymphocyte, Bax and Bcl-2. Apoptotic cells of spleen were detected by means of terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL).

By optical microscopy, white pulps were atrophied and splenic nodules were destroyed after CLP. At 6, 12, 24, 48, 96 hours after CLP, the number of CD(+)T lymphocyte, B lymphocyte and Bcl-2 positive expressed cells in sepsis model group were obviously reduced as compared with sham operation group (all P<0.01). CD8(+) positive lymphocytes were not significant changed (all P>0.05). Apoptotic splenocytes and Bax positive cells were obviously increased compared with those of sham operation group (all P<0.01). Correlation analysis showed that Bcl-2 expression and cell apoptosis was negatively correlated (r=-0.659, P<0.01), but Bax positive cells and apoptosis showed positive correlation (r=0.522, P<0.01).

Disturbance of immunological function exists in the rats with sepsis at 24 hours after CLP. The number of CD4(+) T lymphocyte, B lymphocyte was obviously reduced, apoptotic splenocytes were obviously increased. Bax and Bcl-2 play an important role in apoptosis of splenocytes in sepsis.