The gene coding for these transcript (the bcl-2 gene) seems to be interrupted in most cases of follicular lymphomas carrying the t(14;18) chromosomal translocation.
Nucleotide sequence of a t(14;18) chromosomal breakpoint in follicular lymphoma and demonstration of a breakpoint-cluster region near a transcriptionally active locus on chromosome 18.
All cases showed expression of the B lineage markers T015, B1, and 4G7, and HLA-DR. CALLA was present in all but 1 case, similar to that reported for follicular lymphomas, and much higher than reported for diffuse large cell lymphoma.
In this patient's leukemic cells, the breakpoint of the t(14;18) translocation occurred in the major breakpoint-cluster region of the BCL2 gene and became linked to the JH4 joining-region gene segment of the immunoglobulin heavy-chain locus on the 14q+ chromosome as previously observed in follicular lymphoma.
In the present study, bcl-2 was rearranged in 30% (11 of 37) of follicular lymphomas and 19% (11 of 58) of diffuse lymphomas of follicle center cell lineage.
Immunoreactive bcl-2 protein was observed in the neoplastic cells in almost all the follicular lymphomas, whereas no bcl-2 protein was detected in follicles affected by non-neoplastic processes or in normal lymphoid tissue.
Immunoreactive bcl-2 protein was observed in the neoplastic cells in almost all the follicular lymphomas, whereas no bcl-2 protein was detected in follicles affected by non-neoplastic processes or in normal lymphoid tissue.
To detect occult lymphoma, the polymerase chain reaction (PCR) technique was used to amplify joined bcl-2/JH DNA sequences at the juncture of the t(14:18) translocation in follicular lymphoma.
In this patient's leukemic cells, the breakpoint of the t(14;18) translocation occurred in the major breakpoint-cluster region of the BCL2 gene and became linked to the JH4 joining-region gene segment of the immunoglobulin heavy-chain locus on the 14q+ chromosome as previously observed in follicular lymphoma.
The terminal deoxynucleotidyltransferase-positive phenotype of the patient's leukemic cells further suggests that the pre-B-cell leukemia was derived from a pre-B cell carrying a t(14;18) translocation in the original follicular lymphoma.
Detection of chromosomal translocation t(14;18) within the minor cluster region of bcl-2 by polymerase chain reaction and direct genomic sequencing of the enzymatically amplified DNA in follicular lymphomas.
Twenty-three patients with B-cell non-immunoblastic lymphoma or follicular lymphoma who had a bcl-2 oncogene rearrangement had a poorer response to therapy (7 of 23 with complete remission) than the patients without bcl-2 rearrangement (21 of 26 with complete remission).
Molecular analysis showed that BCL2 was rearranged in the major breakpoint cluster region and had joined into the immunoglobulin heavy chain gene as in follicular lymphoma.
The growth advantage of EBV-infected B cells by overproduction of the BCL-2 protein suggests the direct involvement of the BCL-2 gene product in the pathogenesis of follicular lymphoma.
Molecular analysis showed that BCL2 was rearranged in the major breakpoint cluster region and had joined into the immunoglobulin heavy chain gene as in follicular lymphoma.