This study was to observe whether the apoptotic function of tumor-infiltrating lymphocytes (TIL) is induced in human gastric epithelial dysplasia and gastric adenocarcinoma according to the role of FasL expression.

A total of 56 gastric epithelial dysplasia and gastric adenocarcinoma patients were enrolled in this study: 9 cases of gastric epithelial dysplasia, 18 cases of early gastric carcinomas (EGC) and 29 cases of advanced gastric carcinomas (AGC). Immunohistochemical staining was performed for FasL and CD45, and the terminal deoxynucleotidyl transferase mediated dUTP nick end labelling (TUNEL) method was used to detect cell death in tumor-infiltrating lymphocytes.

1) Positive reactions of FasL to neoplastic cells were 88.9% (8/9) in gastric epithelial dysplasia, 83.3% (15/18) in EGC, and 75.9% (22/29) in AGC. 2) Expression of TIL was decreased in the FasL positive region and was increased in the FasL negative region, and significant expression of TIL was observed in the AGC group (P=0.001). 3) Expression of apoptotic TIL was very similar to the FasL expression, and 100% expression was observed in gastric epithelial dysplasia group. 4) Expression of apoptotic TIL was increased in the FasL positive region and decreased in the FasL negative region, and significant apoptotic expression was observed in the gastric epithelial dysplasia and EGC groups (P=0.0420, P=0.0263, respectively).

These results suggest that FasL is a prevalent mediator of immune privilege in epithelial dysplasia and cancer of the stomach.