Immunological role of human palatine tonsil in Epstein-Barr virus persistence

To determine whether EBV-specific cellular immunity persists and controls EBV in the palatine tonsil, we compared EBV-specific cellular immune responses in the palatine tonsil and peripheral blood. In 32 EBV-seropositive donors, we performed in vitro growth inhibition assays of EBV-induced B-lymphocyte transformation (regression assay). The results showed that EBV-specific cytotoxic T lymphocytes (CTL) precursor frequency was higher in the palatine tonsil than in the peripheral blood. After a first stimulation with autologous lymphoblastoid cell line (LCL), the EBV-specific cytotoxicity of reactivated CTL was higher in the palatine tonsil than in the peripheral blood. Furthermore EBV-specific CTL lines established from the palatine tonsil had significantly higher EBV-specific cytotoxicity in comparison with those from the peripheral blood. Both the EBV-specific CTLs from tonsils and peripheral blood were restricted by HLA class-I determinants. These data indicate that the palatine tonsil, which is frequently exposed to EBV, plays an important role in controlling EBV infection in the oropharynx.