目的研究胃癌及癌旁组织中Ｆａｓ抗原表达与细胞凋亡的关系，探讨Ｆａｓ抗原及细胞凋亡在胃癌发病中的作用．方法采用免疫组织化学及脱氧核糖核酸末端转移酶介导的缺口末端标记（ＴＵＮＥＬ）技术对胃癌组织５０例及癌旁组织３３例中Ｆａｓ抗原表达状态及凋亡细胞进行原位观察和比较．结果胃癌组织Ｆａｓ抗原表达率为４６０％，显著低于癌旁组织的７５８％（χ２＝７２２，Ｐ＜００１）．胃癌组织凋亡细胞指数为５８％，显著低于癌旁组织的１６８％（ｔ＝８６３，Ｐ＜００１）；Ｆａｓ抗原表达阳性的胃癌和癌旁组织凋亡细胞指数显著高于Ｆａｓ抗原阴性组（ｔ＝５１６和ｔ＝３７１，Ｐ＜００１）．结论Ｆａｓ抗原对胃癌及癌旁组织中的细胞凋亡具有促进性调控作用，细胞凋亡调控异常在胃癌发病中可能起重要作用． Objective To study the relationship between Fas antigen expression and apoptosis in gastric cancer and adjacent tissues, and to explore the role of Fas antigen and apoptosis in the pathogenesis of gastric cancer. Methods Immunohistochemistry and terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) technique were used to observe and compare the Fas antigen expression status and apoptotic cells in 50 gastric cancer tissues and 33 adjacent tissues. Results The Fas antigen expression rate in gastric cancer tissues was 46.0%, which was significantly lower than that of adjacent tissues (75.8%) (χ2=722, P<001). The apoptotic cell index of gastric cancer tissue was 5.8%, which was significantly lower than that of tumor adjacent tissue 16.8% (t=8.63, P<0.01); Fas antigen positive expression in gastric cancer and paracancerous tissue apoptotic cells The index was significantly higher than the Fas antigen negative group (t=516 and t=371, P<001). Conclusion Fas antigen can promote the regulation of apoptosis in gastric cancer and adjacent tissues. The abnormal regulation of apoptosis may play an important role in the pathogenesis of gastric cancer.