Expression of Epstein-Barr Virus Gene and Clonality of Infiltrated T Lymphocytes in Epstein-Barr Virus-associated Gastric Carcinoma

BACKGROUND Epstein-Barr virus associated gastric lymphoepithelioma-like carcinoma (LELC) is characterized by the intensive infiltration of lymphoid cells, the presence of EBV, and the better prognosis over typical adenocarcinoma. Thus, it was assumable that viral latent proteins may be responsible for the recruitment of a certain T cell repertoire to EBV-associated gastric carcinoma. METHODS To examine above possibility, EBV gene expression in gastric carcinoma tissues and usage of TCR among the tumor infiltrating lymphocytes were analyzed. RESULTS EBV specific DNA and EBERs RNA were detected in 4 out of 30 patients. RT-PCR analysis revealed that all 4 of EBV-positive tumor tissues expressed EBNA1 mRNA and BARTs and LMP2a was detected only one sample out of 4. However, the EBNA2 and LMP-1 transcripts were not detected in these tissues. CD8(+) T cells were the predominant population of infiltrating lymphocytes in the EBV-positive gastric carcinoma. According to spectra type analysis of infiltrating T cells, 10 predominant bands were detected by TCR Vβ CDR3 specific RT-PCR from 4 EBV-positive tumor tissues. Sequence analysis of these bands revealed oligoclonal expansion of T cells. CONCLUSION These findings suggest that clonally expanded T cells in vivo might be a population of cytotoxic T cells reactive to EBV-associated gastric carcinoma.