These data show that bcl-2 translocation is present in 57% of follicular lymphomas in Chinese patients, and support the notion that bcl-2 translocation is a consistent marker for follicular lymphomas irrespective of ethnic differences.
Two of eight (25%) cases of follicular lymphoma but only one of the 34 (2.9%) cases of diffuse B-cell lymphoma had bcl-2 rearrangement that was detected by pFL-1 probe.
To determine the relative importance of these mutations, we searched for their presence in DNA from the involved lymph nodes of 12 patients with t(14; 18) follicular lymphoma. bcl-2 genomic sequences were specifically amplified by the polymerase chain reaction technique and then directly sequenced.
The bcl-2 gene was also rearranged, consistent with the presence of the t(14;18) (q32;q21) translocation which is typically seen in follicular lymphomas.
In the present study we confirmed, by immunohistologic labeling with polyclonal and monoclonal antibodies, that bcl-2 protein is strongly expressed in many cases of follicular lymphoma and that these neoplastic follicles differ clearly from their nonmalignant counterpart (reactive germinal centres) in which bcl-2 protein is undetectable.
Furthermore, none of the 36 cases of CLL/SLL showed bcl-2 rearrangements, whereas, as expected, 21 of 27 cases of FL had rearrangements of the bcl-2 locus.
Most of human follicular lymphomas possess the t(14;18) chromosome translocation that juxtaposes the IgH gene to the 3' region of bcl-2 in a head-to-tail configuration.
That bcl-2 is involved in a major class of lymphoma in addition to follicular lymphoma implies a role for additional factors responsible for generating the two distinctive clinical and pathologic disease states.
Most of human follicular lymphomas possess the t(14;18) chromosome translocation that juxtaposes the IgH gene to the 3' region of bcl-2 in a head-to-tail configuration.
Rearrangement of the bcl-3 gene was found in only one case; a follicular lymphoma involving the salivary gland that had progressed to a diffuse large cell lymphoma.
Sequence analysis showed the amplified bcl-2/JH fragments to be unique to each individual sample and distinct from 24 sequenced follicular lymphoma-derived t(14;18) junctions, thus excluding contamination artifacts.
The pattern of Bcl-2 staining in follicular lymphoma is the inverse of the pattern in reactive hyperplasia, confirming a role for Bcl-2 immunolocalization in routine diagnosis.
Chromosomal translocations involving the heavy chain immunoglobulin locus on chromosome 14 and a region on chromosome 18 encoding the bcl-2 gene [t(14;18)] are a characteristic and prevalent chromosomal abnormality in nodal malignant lymphoma, particularly follicular lymphoma.
The bcl-3 pattern of expression also bears close resemblance to that of bcl-2 (Gurfinkel et al., 1987), which is frequently associated with human B follicular lymphomas [t(14; 18)] and some chronic lymphocytic leukemias (Adachi et al., 1989; 1990; Adachi & Tsujimoto, 1989).
According to these characteristics, these tumours could be placed in between lymphocytic lymphomas (which usually express CD23) and follicular lymphomas (which commonly lack IgD and CD5 and bear CD10 as well as a t(14:18).
The frequency of VH family use in FL was found to be similar to that reported for normal peripheral blood lymphocytes and is therefore also roughly proportional to VH family size.
According to these characteristics, these tumours could be placed in between lymphocytic lymphomas (which usually express CD23) and follicular lymphomas (which commonly lack IgD and CD5 and bear CD10 as well as a t(14:18).
The bcl-3 pattern of expression also bears close resemblance to that of bcl-2 (Gurfinkel et al., 1987), which is frequently associated with human B follicular lymphomas [t(14; 18)] and some chronic lymphocytic leukemias (Adachi et al., 1989; 1990; Adachi & Tsujimoto, 1989).