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Query: UNIPROT:A9QXG9 (bcl-2)
 7,497 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The gastrointestinal tract is the most common site for extranodal lymphomas, but follicular lymphomas involving the gut are rare. To study their pathologic features and bcl-2 expression, 31 follicular lymphomas of the GI tract were reviewed and unstained paraffin sections from 24 of the cases were immunohistochemically stained using a monoclonal antibody for the peptide product of the proto-oncogene bcl-2. The most common site of lymphoma involvement was the small intestine, especially the terminal ileum. Gastric lymphomas tended to present clinically with symptomatic ulcers and small intestinal lesions presented with obstruction. Five cases involving the terminal ileum or colon had a gross appearance of multitudinous mucosal polyps and were considered to represent examples of "multiple lymphomatous polyposis." Enhanced expression of the bcl-2 oncogenic protein was detectable in lymphoma cells in 75% of cases and at lower levels in normal lymphoid cells in most cases. Small cleaved or mixed cell lymphomas were more likely to show enhanced expression than were large cell cases. Reactive germinal centers showed no bcl-2 staining. It is concluded that follicular GI lymphomas are associated with distinctive pathological features. In their tendency to express bcl-2, these neoplasms resemble their lymph node-based counterparts. Immunohistochemical staining for enhanced bcl-2 expression is of potential diagnostic utility in distinguishing between follicular lymphoma and follicular lymphoid hyperplasia in the gastrointestinal tract. The relevance of the results to lymphoma of mucosa-associated lymphoid tissue (MALT) is discussed.
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PMID:Follicular lymphomas of the gastrointestinal tract. Pathologic features in 31 cases and bcl-2 oncogenic protein expression. 137 56

A morphological, immunophenotypic and ultrastructural study, cell cycle estimation, DNA and cytogenetic analysis were performed in ten cases of B-MALT lymphomas. Five had low grade lymphoma and five had high grade. Low and high grade cases showed the same cells but in different percentages: These included centrocyte-like cells with occasional monocytoid cytoplasmic changes, and centroblast-like cells. However, in high grade cases more dysplastic and large cells were present. All cellular types showed an important development of rough endoplasmic reticulum. In all cases a large panel of monoclonal antibodies was employed to study the B-cell immunophenotype. Ki-67 positivity ranged from 5% to 30% in low-grade cases and from 50% to 70% in high-grade cases. Gene rearrangement analysis showed rearrangement with Jh probe and half of the cases were also rearranged with the Kde probe (Kappa constant chain gene). A rearrangement banding pattern with TCR genes was not present in any of the cases. Cytogenetic study showed complex alterations in high grade cases and a normal karyotype in low grade lymphomas. Only one case had rearrangement for the bcl-2 probe.
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PMID:A multiparametric study of malignant lymphoma of mucosa associated lymphoid tissue (MALT). 149 75

We have examined 107 cases of B-cell lymphoma for the t(14;18) translocation, characteristically described in follicular lymphoma. B-Cell lymphomas of extranodal origin, and in particular malignancies derived from mucosa-associated lymphoid tissue (MALT), were compared with node-based lymphomas of follicular and diffuse morphology. Cytogenetic techniques were supplemented by molecular analysis using probes which recognize both the major and the minor breakpoint regions of the bcl-2 gene located on chromosome 18 (q21). t(14;18) was detected in 55 per cent of follicular and 27 per cent of diffuse B-cell lymphomas thought to be of follicle centre cell origin. Cytogenetics and molecular analysis proved equally effective in demonstrating the translocation. t(14;18) was not observed in the 36 extranodal lymphomas examined, of which 20 were characterized histologically as lymphomas of MALT, using either technique. In addition, 30 cases demonstrated only a germline band when probed with a bcl-3 probe specific for t(14;19), a translocation observed in chronic lymphocytic leukaemia (CLL). Cytogenetic abnormalities were detected in all cases of extranodal lymphoma, although no consistent abnormality was observed. Numerical abnormalities of chromosomes 3, 6, 16, and 18; structural abnormalities of chromosomes 2, 6, 8, and 9; and small marker chromosomes were frequently seen. This study provides data which suggest that different genetic events are involved in the development of lymphoma of MALT from those giving rise to follicle centre cell lymphomas.
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PMID:Cytogenetic and molecular studies of t(14;18) and t(14;19) in nodal and extranodal B-cell lymphoma. 156 Mar 13

High-grade B-cell lymphomas, whether originated in a lymph node or in mucosa-associated lymphoid tissue (MALT), show similar morphologic traits, a fact that has fueled a long-running controversy about whether they represent different entities. They differ, however, in that some high-grade MALT lymphomas show less aggressive clinical behavior, a focal low-grade component being identified in some of them. In a search for bcl-2 protein expression, we have found a significant difference between nodal (39/48) and MALT high-grade B-cell lymphoma (1/15) (P less than 0.01). Bcl-2 gene product is an inner mitochondrial membrane protein able to give a survival advantage to B-cell lines by blocking programmed cell death. This protein is usually expressed by memory or resting B cells, most activated B cells being bcl-2 negative, except in lymph-node-originated high-grade B-cell lymphomas, which appear to be mainly bcl-2 positive. Presence of bcl-2 protein in nodal large-cell lymphomas seems to be independent of a t(14;18) translocation, only being found in 19 to 28% of these lymphomas, although it constitutes a definite difference between both tumors, suggesting the existence of different molecular genetic characteristics and pathogenesis, and is possibly related to the more aggressive clinical behavior of nodal high-grade tumors.
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PMID:Different bcl-2 protein expression in high-grade B-cell lymphomas derived from lymph node or mucosa-associated lymphoid tissue. 195 37

The formation of neoplastic B-cell follicles is universally accepted as diagnostic of a follicle centre cell (FCC) lymphoma. Low-grade B-cell lymphomas of mucosa-associated lymphoid tissue (MALT) are characterized by a diffuse infiltrate of cells of uncertain lineage known as "centrocyte-like" cells because of their resemblance to centrocytes (small cleaved cells). Some MALT lymphomas, however, contain numerous follicles and may even have a predominantly follicular appearance. These follicles may be reactive or show immunoglobulin (Ig) light-chain restriction, indicating their neoplastic nature. We have proposed that these neoplastic follicles are not composed of follicle centre cells but result from colonization of reactive follicles by CCL cells. In this study, the immunophenotype and genotype of 10 primary gastrointestinal lymphomas with a follicular component have been determined. One case exhibited the morphological, immunophenotypic, and genotypic features of FCC lymphoma (Ig light-chain restriction, CD10+, KB61 (CDw32)-, Jh, and bcl-2 gene rearrangement). Neoplastic follicles in the remaining nine cases, which showed the features of MALT lymphoma, were of a different phenotype (Ig light-chain restriction, CD10- KB61(CDw32)+), and these lymphomas showed Jh but not bcl-2 gene rearrangement. Taken in conjunction with the morphological features, these findings suggest that in these cases the neoplastic follicles formed as the result of colonization of previously reactive follicles by neoplastic CCL cells. Thus, not all lymphomas containing neoplastic follicles are of FCC origin. Follicular colonization, as seen in low-grade MALT lymphomas, is likely to be a recapitulation of an as yet undescribed normal immunological phenomenon that may involve marginal zone B cells.
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PMID:Follicular colonization in B-cell lymphoma of mucosa-associated lymphoid tissue. 195 41

Sixteen cases of gastrointestinal B- and T-cell lymphoma were investigated for clonal rearrangements of immunoglobulin and T-cell receptor genes. In all cases the immunogenotype data corresponded well with the immunohistochemical findings, thus confirming the biologic heterogeneity of these lymphomas. Some cases could be distinguished by additional heterogeneity in their genotype which could not be detected by immunohistochemical methods. Moreover, the B-cell lymphomas were studied for the presence of the chromosomal translocations t(11;14) and t(14;18) using probes for bcl-1 and bcl-2 genes, respectively. While bcl-1 rearrangement was not present in these gastrointestinal lymphomas, one case of diffuse low-grade lymphoma of mucosa-associated lymphoid tissue and three cases of centroblastic lymphoma (diffuse large cell) could be shown to have detectable bcl-2 rearrangement.
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PMID:Genomic analysis of T-cell receptor and immunoglobulin antigen receptor genes and breakpoint cluster regions in gastrointestinal lymphomas. 224 41

The bcl-2 gene rearrangement representing t(14:18) chromosomal translocation is the most frequent karyotypic abnormality in non-Hodgkin's lymphomas of follicle center-cell lineage. By using three bcl-2 DNA probes, 21 cases of non-Hodgkin's B cell lymphoma arising from gastrointestinal mucosa and eight cases of follicular lymphomas were examined. No rearrangement of the gene could be detected in the group of gastrointestinal lymphomas, although it was identified in 75% of the follicular lymphomas. The findings suggest that these two groups of lymphomas are not a family at genetic level and support the earlier suggestion that B cell lymphomas arising from gastrointestinal mucosa-associated lymphoid tissue are not of follicle center-cell lineage.
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PMID:The bcl-2 gene in primary B cell lymphoma of mucosa-associated lymphoid tissue (MALT). 267 27

Diffuse large B cell lymphomas (DLBLs) represent a heterogeneous collection of aggressive non-Hodgkin's lymphomas that can arise either de novo or as a result of transformation from chronic lymphocytic leukemia, small lymphocytic lymphoma, follicular lymphomas, or lymphomas of mucosa-associated lymphoid tissue. A small percentage of DLBLs express the CD5 antigen. The majority of these cases have evolved from a pre-existing low grade non-Hodgkin's lymphoma (Richter's syndrome). However, we identified and characterized nine CD5-positive DLBLs in which the patients did not have a previous history or concomitant evidence of chronic lymphocytic leukemia, small lymphocytic lymphoma, follicular lymphoma, or mucosa-associated lymphoid tissue-associated non-Hodgkin's lymphoma, suggesting that they arose de novo. All nine cases expressed CD20 and monotypic immunoglobulin, all eight cases examined expressed CD19, CD22 and CD43, eight of the nine cases expressed HLA-DR, and two of eight cases expressed CD11c. None of the cases expressed CD3, CD10, CD11b, CD21, CD23 or CD30. CD5 expression by these cells was found to be identical to that of CD5-positive B cell chronic lymphocytic leukemia by quantitative polymerase chain reaction analysis of CD5 mRNA. These nine de novo CD5-positive DLBLs exhibited clonal immunoglobulin heavy and light chain gene rearrangements but lacked integration of the Epstein-Barr virus genome and structural alterations of the bcl-1, bcl-2, c-myc, H-ras, K-ras, and N-ras proto-oncogenes and the p53 tumor suppressor gene. However, bcl-6 proto-oncogene rearrangement, which is involved in chromosome band 3q27 aberrations, was found in four cases (44.4%). This is comparable with the frequency of bcl-6 gene rearrangement in CD5-negative DLBL. In contrast, bcl-6 gene rearrangement was absent in six cases of DLBL associated with Richter's syndrome. These findings suggest that de novo CD5-positive DLBLs are genotypically similar to CD5-negative DLBLs and may be pathogenetically distinct from the DLBLs associated with Richter's syndrome.
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PMID:De novo CD5-positive and Richter's syndrome-associated diffuse large B cell lymphomas are genotypically distinct. 754 11

Bcl-2 protein expression was studied in a series of 58 MALT lymphomas using a monoclonal antibody which recognises this protein in routinely processed paraffin embedded tissue. Thirty-three of 58 cases showed heterogeneity for bcl-2 expression, 18 of 58 cases were bcl-2 positive and 7 of 58 were bcl-2 negative. High grade and low grade MALT lymphomas showed different patterns of staining. All 21 low grade tumours were positive for bcl-2, though in seven cases only a proportion of the neoplastic cells expressed this protein. In the 37 high grade tumours the majority of the neoplastic cells were negative with seven cases showing no reactivity at all. These findings give further support to the theory that MALT lymphomas differ in pathogenesis to nodal lymphomas and suggest that the good prognosis of MALT lymphomas may partly be explained by the fact that they maintain a normal pattern of bcl-2 expression.
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PMID:Heterogeneity of bcl-2 expression in MALT lymphoma. 771 86

In lymphoproliferative diseases of the skin, DC have a key role in T- and B-cell homing. Furthermore, DC alterations may have a pathogenic role in the natural history of specific disorders, either in the neoplastic lymphoid cell progression or in antitumoral lymphocyte reaction. Finally, the morphoantigenic and topographic features of DC may have diagnostic and histogenetic relevance in specific conditions. In CTCL, dermal CD1a+ DC ("indeterminate cells") seem to play a significant role in the neoplastic progression of MF, whereas the possible pathogenetic role of specific alterations of epidermal LC is yet to be proven. Recently, a possible implication of DD (resident, perivascular factor XIIIa+/CD1a- DC) in the pathogenesis of MF has been also suggested. The presence and possible significance of DC in CTCL non-MF are presently poorly studied. At present, DC number, distribution, and phenotype seem possibly useful in the differential diagnosis between CTCL and pseudo-CTCL, but this hypothesis has to be adequately confirmed. CBCL has been recently proposed as a unique type of clinically low-grade lymphoma, namely, skin-associated lymphoid tissue (SALT)-related B-cell lymphoma. Both SALT- and mucosa-associated lymphoid tissue (MALT)-related B-cell lymphoma share with a peculiar nodal lymphoma of follicle mantle origin (parafollicular-monocytoid lymphoma) the nonaggressive clinical behavior and the uniform phenotype (CD5-, CD10-) and genotype (lack of bcl-2 gene rearrangement) of neoplastic B cells, despite the wide variability of cytomorphologic appearances. The putative origin of CBCL is further supported by the typical CD14-, nerve growth factor receptor (NGFr)+ immunophenotype of DRC. Moreover, the immunophenotype and architectural fashion of DRC are interesting clues to the differentiation between neoplastic and true reactive folliclelike nodules and may be of help in the differential diagnosis between CBCL and B-cell pseudolymphoma as well as in the correct interpretation of lesions showing monoclonal proliferations of B cells accompanied by polyclonal follicular reactions.
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PMID:Dendritic cells in T- and B-cell proliferation in the skin. 804 37


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