BCL2 gene activation and protein expression in follicular lymphoma: a report on 64 cases

Rearrangements of the BCL2 gene and expression of bcl-2 protein were analyzed in a series of 64 cases of follicular lymphomas in order to establish a relationship between the rearrangements and the protein overexpression. Of the 64 cases, 41 showed BCL2 rearrangement involving one of the three breakpoint clusters: 30 in mbr, eight in mcr, and three in vcr. A double rearrangement mbr+vcr was detected in two cases. Twenty cases with bcl-2 protein expression in tumor cells exhibited no apparent rearrangement, suggesting the possible existence of other mechanisms activating the gene. Interestingly, expression of the LMP1 protein, the Epstein-Barr virus (EBV) encoded gene, whose capacity to induce BCL2 has been recently demonstrated, was only found in 2/41 cases in which BCL2 was rearranged. These data suggest that EBV infection is not an important mechanism in the activation of BCL2 in follicular lymphoma.