HIGH EXPRESSION OF THE EPSTEIN-BARR-VIRUS LATENT PROTEIN EB NUCLEAR ANTIGEN-2 ON PYOTHORAX-ASSOCIATED LYMPHOMAS

Pyothorax-associated lymphoma (PAL) is a rare tumor associated with lo ng-standing tuberculous pyothorax. Most of these lymphomas are B-cell lymphomas of high-grade malignancy. Over 50 cases have been reported i n Japan, but no cases have been described in Western countries. Its pa thogenesis remains unknown. We studied immunohistologically the expres sion of Epstein-Barr virus- (EBV) encoded latent gene products, EB nuc lear antigen-2 and LMP-1, in four cases of PAL Fifty B-cell lymphomas unrelated to pyothorax, and five EBV-bearing lymphoblastic tumors prod uced in severe combined immune deficient mice (severe combined immune deficient-EBV+ tumors) were also studied as controls. Marked expressio n of EB nuclear antigen-2 was demonstrated on all four PALs. LMP-1 was also present in all cases, but both the staining intensity and the nu mber of stained cells remained less than on severe combined immune def icient-EBV+ tumors. Neither EB nuclear antigen-2 nor LMP-1 was observe d in the 50 control B-cell lymphomas. Additional molecular genetic ana lysis revealed that EBVs are incorporated into each PAL clonally. Thes e results confirm the definite association of EBV with PALs, although the significance of weak expression of LMP-1 awaits further study.