Expression of bcl-3 in chronic lymphocytic leukemia correlates with trisomy 12 and abnormalities of chromosome 19.

The bcl-3 gene at chromosome 19q13 encodes a member of the IkB family involved in regulating the nuclear factor kB pathway. Originally identified by its involvement in the t(14:19)(q32;q13), bcl-3 expression recently has been reported in 12% of non-Hodgkin lymphomas and 41% of Hodgkin lymphomas. Because the t(14;19) is detected most commonly in chronic lymphocytic leukemia (CLL), we assessed for bcl-3 expression using immunohistochemical analysis in 72 CLL cases with immunophenotypic and cytogenetic data. Of 72 CLL cases, 12 (17%) were bcl-3+. Expression of bcl-3 correlated with an atypical immunophenotype, defined using the World Health Organization scoring system. Expression also correlated with trisomy 12 and chromosome 19 abnormalities but was not limited to cases with the t(14:19)(q32;q13). Although the mechanism of bcl-3 expression is unclear, these results raise the possibility that bcl-3 may be involved in the pathogenesis of this subset of tumors and could be a potential target for investigational therapies.