Low frequency of apoptosis in Epstein-Barr virus-associated gastric carcinoma with lymphoid stroma

In order to understand the character of Epstein-Barr virus (EBV)-associated gastric carcinoma with lymphoid stroma (GCLS), we examined cell proliferation and death in comparison with gastric carcinoma without prominent lymphoid stroma (conventional gastric carcinoma). The EBV-encoded small RNA I (EBER-1) and apoptotic cells were examined by in situ hybridization (ISH) and by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end-labeling (TUNEL), respectively, on formalin-fixed paraffin-embedded surgical specimens from 22 GCLSs and 23 conventional gastric carcinomas. Immunostaining was performed for the detection of Ki-67 antigen (Ki-67), P53 protein (P53) and bcl-2 oncoprotein (BCL-2). The percentages of apoptotic and Ki-67-positive cells were expressed as apoptotic indices (AI) and Ki-67 labeling indices (KI), respectively. EBER-1 was detected in 19 (86%) GCLSs in contrast to none in conventional carcinomas. Mean AI was 1.8 +/- 0.6 in the EBER-1-positive GCLSs and 3.3 +/- 1.7 in the conventional gastric carcinomas, the value being significantly lower in the former (p < 0.01). Mean KI was 40.0 +/- 10.8 in the GCLSs and 48.5 +/- 9.1 in the conventional gastric carcinomas, the value being significantly lower in the former (p < 0.05). P53 expression showed no significant difference between the 2 categories of carcinoma.