The Role of Epstein-Barr Virus as a Causative Agent in Chronic Tonsillitis and Tonsillar Hypertrophy

Shin, Hyun Soo; Kim, Ji Eun; Lee, Bong Jae

Abstract

BACKGROUND AND OBJECTIVES
The palatine tonsil consists of lymphoid cells, and it is the frequent site of upper respiratory tract infection. We aimed to investigate the role of Epstein-Barr virus (EBV) as a pathogen in chronic tonsillitis and tonsillar hypertrophy. MATERIALS AND METHOD: Eighty four tonsil specimens from 84 patients with chronic tonsillitis or tonsillar hypertrophy were investigated with in situ hybridization for EBV and immunohistochemical staining for late membrane protein 1 (LMP1) and CD21. Correlation between EBV positivity/density (graded as a scale from 0 to 3) and clinical parameters was investigated. RESULTS: EBV-encoded small nuclear RNA (EBER) positive lymphocytes were found in the interfollicular zone of tonsils in 66 cases (79%) out of 84 tonsils, whereas surface epithelial cells were negative for EBV. Cases of the higher EBV density had significantly larger tonsils than those of the lower EBV density with statistical significance (p<.01), and the higher density (grade 2, 3) was more frequently observed in the male tonsils than in female ones (20 vs. 8, p<.05). LMP1 was observed in only five tonsils as a few positive cells. Tonsillar epithelial cells and lymphoid cells were uniformly negative for CD21. CONCLUSION: This study demonstrates that EBV resides in the tonsillar lymphocytes of most patients with chronic tonsillitis in Korea and might contribute to the tonsillar hypertrophy. The very low incidence of LMP1 positivity suggests that EBV-infected tonsillar lymphocytes may maintain type 1 latency and have relatively low risk of cellular transformation.