Title Pyothorax-associated Lymphoma : Loss of Epstein-Barr Virus Nuclear Antigen-3B Protein Expression as a Result of Mismatch Repair Phenotypes

s : Pyothorax-associated lymphoma (PAL) is an EBV-associated lymphoma, which develops in the pleural cavity of immunocompetent patients with an over-20-year history of pyothorax. PAL tumor cells taken from a 72-year-old man revealed having mismatch repair (MMR) phenotype and expression of all Epstein-Barr virus latent genes except EBNA-3B. EBNA-3B gene in the derived cell line had frameshift mutation in mononucleotide repeats, indicating that EBNA-3B was the target for the MMR phenotype. Because EBNA-3B works as target antigens for host cytotoxic T-lymphocyte (CTL) responses via two HLAA11-restricted epitopes, loss of EBNA-3B expression may contribute for PAL cells to escape from host immune surveillance in the present case.