BCL6 LAZ3 REARRANGEMENTS IN POSTTRANSPLANT LYMPHOPROLIFERATIVE DISORDERS/

Post-transplant lymphoproliferative disorders (PTLD) are well-known co mplications of iatrogenic immune deficiency and are thought to result from the proliferation of B cells infected by the Epstein-Barr virus ( EBV). Some large cell lymphomas occurring in the general population ca rry a rearrangement of the Bcl6/Laz3 zinc-finger-encoding gene, 15 EBV -associated PTLD were tested for the presence of Bcl6/Laz3 rearrangeme nts by Southern blot analysis using two specific probes (F370, F372). One out of 15 cases displayed a rearranged band independent of the ger mline one. In contrast, 10 lymphoblastoid cell lines and one lymphobla stoid cell line passaged in an SCID mouse carried only germline allele s of Bcl6/Laz3 after Southern blot hybridization. This indicates that genetic abnormalities may also play an important role in the developme nt of some PTLD.