FasL的表达在结直肠癌免疫逃逸中的意义

目的研究结直肠癌中Fas配体（FasL）的表达及其在结直肠癌免疫逃逸中的意义。方法采用免疫组织化学染色法，检测80例结直肠癌组织中FasL表达及肿瘤浸润淋巴细胞（TIL）的数量。应用原位杂交法，检测80例结直肠癌组织连续切片的FasL的。RNA的表达。采用脱氧核糖核酸末端转移酶介导的缺口末端标记技术（TUNEL），对80例结直肠癌组织中凋亡的TIL及肿瘤细胞进行观察。结果80例结直肠癌组织FasL表达程度不等，不论是在同一组织切片不同部位或两组织切片间相比，FasL表达程度和范围都不均匀。FasL的mRNA的表达部位与FasL蛋白的表达部位相对应。FasL表达程度高的组织的TIL计数低于FasL表达低的组织（P〈0．05），同时其TIL凋亡指数高于FasL表达低的组织，而结直肠癌细胞的凋亡指数低于FasL表达程度低的组织（P〈0．01），TIL凋亡指数与胃癌细胞的凋亡指数呈负相关（r=-0．631，P〈0．01）。结论全占直肠癌细胞可通过表达FasL，诱导TIL发生凋亡，反击机体免疫系统，这可能是结直肠癌免疫逃避的重要机制之一。

The significance of FasL expression in immune escape of colorectal carcinoma

Objective To study the FasL expression in colorectal carcinoma and its significance in immune escape of cancer.Methods The expression of FasL protein and the number of TIL in 80 specimens of colorectal carcinoma were detected by immunohistochemitry.The mRNA of FasL was measured by in situ hybridization in the consecutive tissue slices of 80 colorectal carcinomas respectively.Using terminal deoxynucleotidyl transferase-mediaed dUTP nick end labeling (TUNEL),apoptotic cells were detected in 80 specimens of colorectal carcinoma.Results The expression of FasL were detected in all 80 specimens,but it was not even in the same or among different tissues.In the consecutive tissue slices, the location of expression of FasL protein corresponded with that of FasL mRNA.In those FasL extensive expression, the number of TIL was lower than that of FasL weak expression (P<0.05),and the apoptotic index (AI) of TIL was higher and the AI of tumor cells was lower than that of FasL weak expression respectively (P<0.01).The AI of TIL was correlated with the AI of tumor cells (r=-0.631,P<0.01).Conclusion Colorectal carcinoma cells can induce the apoptosis of TIL through the expression of FasL,which can counterattack the immune system.This maybe a mechanism of immune evasion in colorectal carcinoma.