创伤性脑损伤后大鼠外周血CD8的变化

目的:探讨外周血CD8在创伤性脑损伤后的变化特点。方法:改良Feeney's自由落体打击法制备创伤性脑损伤模型;ELISA检测大鼠血清中神经元特异性烯醇化酶(NSE)和CD8的含量,双变量分析两者的相关性;Western blot法检测大鼠血液淋巴细胞FasL蛋白的表达。结果:颅脑外伤后大鼠血清CD8升高滞后于NSE。大鼠伤后1 d血清NSE水平即显著升高,伤后3 d达到峰值,随后逐渐下降;大鼠血清CD8在伤后3 d开始升高,峰值出现在伤后7 d,随后逐渐下降。统计分析显示伤后1 d、3 d、7 d的血清的NSE与伤后3 d、7 d、14 d的血清CD8含量变化呈现正相关。但伤后不同时间大鼠血液淋巴细胞FasL蛋白表达的差异均无统计学显著性。结论:创伤性脑损伤后释放入血的NSE刺激机体免疫应答,引起外周血CD8增多,推测其可能与创伤性脑损伤后继发性损伤的免疫应答有关。

Variation of CD8 after traumatic brain injury in serum of rats

AIM: To explore the character of CD8 after traumatic brain injury (TBI) in peripheral blood. METHODS: Improved Feeney's free-fall method was used to set up traumatic brain injury model. The levels of neuron-specific enolase (NSE) and CD8 in the serum of the rats were detected by ELISA. The correlation of both NSE and CD8 in the serum was analyzed by Pearson product-moment correlation. The FasL expression in the lymphocytes of peripheral blood was determined by Western blot. RESULTS: The elevated level of CD8 lagged behind the level of NSE in the serum after TBI. The serum level of NSE was significantly increased at the 1st day after TBI and reached a peak at the 3rd day, subsequently gradually decreased to a lower level; the serum level of CD8 was increased at the 3rd day after TBI, and reached a peak at the 7th day, then gradually decreased. The serum levels of NSE at 1st, 3rd and 7th days were positively correlated with the serum level of CD8 at 3rd, 7th and 14th days. However, the FasL expression in the CD8⁺ lymphocytes of peripheral blood showed no variation at different time points after TBI. CONCLUSION: NSE in the serum released from neural tissues after TBI stimulates immune response and induces the augmentation of CD8 in peripheral blood, which may be a cause of secondary injuries in the brain.