Bcl2-negative follicular lymphomas frequently have Bcl6 translocation and/or Bcl6 or p53 expression

Bcl2 is an important protein involved in the pathogenesis of follicular lymphoma (FL). However, approximately 10% of FL cases do not express Bcl2. The present study was designed to compare gene aberrations, prosurvival gene expression, apoptosis and proliferation rates in Bcl2-positive and -negative FL cases. Bcl2 translocation and Bcl6 translocation were detected and compared using fluorescence in situ hybridization (FISH). A tendency for Bcl6 translocation to occur was found more frequently in Bcl2-negative FL than in the Bcl2-positive cases. The expression of Bcl-X, BAX, p53, Bcl6 was analyzed by immunohistochemistry. Bcl2 family proteins Bcl-X and BAX were expressed similarly in the two FL types. In some cases of Bcl2-negative FL there was high expression of Bcl6 or p53 but no such Bcl2-positive FL cases were detected. Furthermore, there was an inverse relationship between the expression of Bcl6 and p53. These results indicate that the Bcl6 translocation occurs more frequently in Bcl2-negative FL. Furthermore, other prosurvival proteins such as p53 and Bcl6 may play an important role in the pathogenesis of Bcl2-negative FL.