The presence and subtype of Epstein-Barr virus in B and T cell lymphomas of the sino-nasal region from the Osaka and Okinawa districts of Japan

Abstract

Background: Association between Epstein-Barr virus (EBV) and human malignancies, including sino-nasal lymphoma (SNL), has been suggested. EBV-associated malignancies have been reported to show distinct geographic distribution.

Experimental design: In the present study, the presence of an EBV genome and its subtypes (type A and B) were examined in 52 cases of sino-nasal lymphomas of B and T cell type collected from two areas of Japan: Osaka, situated on the mainland, and Okinawa, islands situated in a southwest part of Japan with a subtropical climate. Our previous epidemiologic study showed that the frequency of nasal T cell lymphoma was 3.5 times higher in Okinawa than in Osaka.

Results: There were no prominent differences in age distribution or sex ratio between these two areas: age ranged 8 to 85 (median 54) years, with a male to female ratio of 1.26:1. Immunophenotypically, 27 cases were B cell type (20 Osaka, 7 Okinawa), 20 were T cell type (9 Osaka, 11 Okinawa), and 5 were undefined. By PCR, EBV positivity in throat washings of normal individuals in Osaka and Okinawa was 52 and 53%, respectively, with marked preponderance of subtype A in both areas. EBV genome was found in 6 of 15 cases (40%) and 4 of 5 cases (80%) of nasal B and T cell lymphomas in Osaka and in 3 of 7 cases (43%) and 7 of 7 cases (100%) in Okinawa, showing the different frequencies of positivity by immunophenotype but not by district. All but one patient had type A EBV. The in situ hybridization confirmed the results of PCR as positive signals in the nucleus of proliferating cells. Latent membrane protein-1 was expressed in 13 of 22 cases (59%).

Conclusions: These findings suggest that EBV, exclusively type A, might be a causative factor in sino-nasal lymphoma of not only T cell but also B cell type in Japan.