SELECTIVE OUTGROWTH OF A POSTTRANSPLANT B-IMMUNOBLASTIC LYMPHOMA EXPRESSING A LATENT MEMBRANE PROTEIN-1 DELETION VARIANT

Background. Posttransplant lymphoproliferative disorders are generally associated with Epstein-Barr virus (EBV) and are of B cell origin. We report the case of a B-immunoblastic lymphoma that developed in a pre transplantation EBV-seronegative woman 4 months after kidney transplan t from her HLA-haploidentical brother. The patient successfully underw ent immunotoxin therapy for lymphoma and has been in remission for 36 months. Methods. Latent EBV genomes were identified by polymerase chai n reaction, and the purified amplification products were directly sequ enced with [S-35]dATP. Results. Molecular analysis of the latent membr ane protein (LMP)1 oncogene of EBV, which was expressed in most tumor cells, revealed a 30-base pair deletion. No wild-type LMP1 sequences w ere found. Analysis of peripheral blood mononuclear cells from the EBV -seropositive donor showed the presence of both the LMP1 deletion vari ant and the wild-type sequence. The LMP1 deletion variant and the wild -type sequence were also identified within peripheral blood mononuclea r cells of the EBV-seroconverted kidney recipient 20 months after lymp homa therapy. Conclusion. This pattern is consistent with a natural gr owth advantage of B cells expressing the LMP1 deletion variant in the immunocompromised host.