Relationship between Fas-ligand expression on carcinoma cell and cytotoxic T-lymphocyte response in lymphoepithelioma-like cancer of the stomach
✍ Scribed by Tohru Kume; Koichi Oshima; Yuichi Yamashita; Takayuki Shirakusa; Masahiro Kikuchi
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- French
- Weight
- 810 KB
- Volume
- 84
- Category
- Article
- ISSN
- 0020-7136
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✦ Synopsis
The Fas/Fas-ligand (Fas-L) system is involved in the induction of apoptosis and mediates T-cell cytotoxicity. We investigated the Fas/Fas-L system and cytotoxic T lymphocytes (CTLs) in 30 lymphoepithelioma-like cancer of the stomach (LECS) in order to understand the immune evasion of the tumor cells. Epstein-Barr virus (EBV) was detected in 15 cases in 30 LECSs. The expressions of Fas and Fas-L in tumor cells, and TIA-1, CD4, CD8 and CD56 in lymphocytes were examined by immunohistochemical staining. Apoptosis of tumor cells and lymphocytes was detected by the terminal deoxynucleotidyl-mediated dUTP-nick end labeling method (TUNEL). Expression of Fas and Fas-L was detected in tumor cells in 10 and 17 LECS, respectively. CTL consisted predominantly of CD8 (CD8 ؉ G CD4 ؉ ), whereas natural killer (NK) cells were detected in 4 cases only. In Fas-L-positive tumors, the TIA-1-positive lymphocyte count was significantly lower (p F 0.05) and the number of apoptotic lymphocytes was significantly higher (p F 0.05) than in Fas-L-negative cases. The number of TIA-1-positive lymphocytes in EBV ؉ cases was significantly higher than that in the EBV ؊ tumors (p F 0.05). The number of apoptotic tumor cells in EBV ؉ tumors was significantly lower than in EBV ؊ cases (p F 0.01). Our results suggest that in LECS, tumor cells expressing Fas-L may evade the immune attack by killing lymphocytes through the Fas/ Fas-L system. However, in EBV ؉ LECS tumors, our results indicate that a high number of CTL is associated with a reduction in the number of apoptotic tumor cells. Our findings indicate that the Fas/Fas-L system plays a role in immune evasion of tumor cells in EBV ؉ tumors.