凋亡调控基因Mcl-1和bcl-2在反应性及肿瘤性淋巴组织中的表达及其意义

目的 :观察Mcl 1和bcl 2在反应性和肿瘤性淋巴组织中的表达 ,探讨其在肿瘤发生和发展过程中的作用。方法 :收集临床资料完整的反应性淋巴组织增生石蜡包埋标本 36例 ,非霍奇金淋巴瘤(NHL) 78例和霍奇金病 (HD) 10例 ,采用免疫组化方法染色观察Mcl 1和bcl 2表达。结果 :反应性淋巴组织中Mcl 1阳性细胞主要分布在生发中心和滤泡间区 ,而bcl 2阳性的套区淋巴细胞为Mcl 1阴性。 78例NHL中 ,有 5 7例不同程度地表达Mcl 1蛋白 ,5 3例表达bcl 2 ,B细胞肿瘤中两者阳性率高于T细胞肿瘤。 10例HD中有 9例Mcl 1 bcl 2阳性。结论 :Mcl 1作为一种凋亡抑制基因在淋巴组织的表达不同于bcl 2 ;鉴于两者在淋巴组织肿瘤中的广泛分布 ,提示其在淋巴瘤细胞凋亡调控中可能起着重要作用     

Circulating buttock cells in non-Hodgkin's lymphoma

Leukemic B cells with a characteristically sharp nuclear cleft seemingly dividing the nucleus into two or more parts have been entitled "buttock cells" and are subject of this study. These cells were found in leukemic non-Hodgkin's lymphomas (NHL) and usually have been related to follicular center cell lymphomas. However, buttock cells also closely resemble cells present in intermediate lymphocytic lymphoma (ILL) and mantle zone cells of reactive lymphoid tissues. Ultrastructurally, it became apparent that the separate nuclear lobes of buttock cells were connected by chromatin bridges. Immunophenotypically, circulating buttock cells had a variable phenotype, which may indicate either a follicle center or mantle zone origin. The use of CD5 and FMC7 monoclonal antibodies might be of discriminative help. These leukemic NHL have to be differentiated from classical chronic lymphocytic leukemia (CLL) with help of cytomorphology and immunophenotyping, since the former usually have a worse prognosis and generally will require a different treatment.     

抗凋亡蛋白Bcl—2在非霍奇金淋巴瘤中的表达,分布及其临床意义

研究抗凋亡蛋白Ｂｃｌ－２在非霍奇金淋巴瘤（ＮＨＬ）中的表达、分布及其临床意义。方法采用４重ＰＡＰ免疫组织化学法,对比分析了１２例反应性淋巴滤泡增生与７１例ＮＨＬ的常规石蜡包埋淋巴结组织中Ｂｃｌ－２蛋白的表达与分布。结果（１）９３．０％Ｔ、Ｂ淋巴细胞性ＮＨＬＢｃｌ－２蛋白阳性。（２）８／９例滤泡中心起源的弥漫型ＮＨＬ中,Ｂｃｌ－２蛋白局限于中心细胞,而中心母细胞多为阴性。（３）５／１０例呈浆细胞样分化趋势的弥漫性大Ｂ细胞ＮＨＬ,Ｂｃｌ－２蛋白表达增强。（４）７例滤泡型ＮＨＬ中,Ｂｃｌ－２蛋白主要定位于瘤性滤泡中央,而其周围则相对稀疏。相反,生理性淋巴滤泡中,Ｂｃｌ－２蛋白则主要分布于套区,生发中心均为阴性。结论Ｔ、Ｂ淋巴细胞ＮＨＬ均能表达Ｂｃｌ－２;Ｂｃｌ－２表达可能与ＮＨＬ分化水平相关;Ｂｃｌ－２蛋白免疫组化染色有助于鉴别反应性淋巴滤泡增生过长与滤泡型淋巴瘤。     

Expression of the activation antigen, 4F2, by non-Hodgkin's lymphomas of B-cell phenotype.

The monoclonal antibody, 4F2, which reacts with an antigen expressed by activated and proliferating cells, was applied to frozen sections of nine reactive lymphoid lesions, 146 B-cell non-Hodgkin's lymphomas (NHL), and six plasmacytic neoplasms. In reactive cases, the 4F2 antigen was expressed by germinal center cells and interfollicular immunoblasts, the activated or proliferating lymphoid cells, and histiocytes. In the malignant cases, the 4F2 antigen was expressed by 94 (64%) B-cell NHL and all six plasma cell tumors. The incidence of positivity and intensity of expression loosely correlated with the three morphologic grades of NHL identified in the Working Formulation. Approximately one half of all low-grade lymphomas, two thirds of intermediate-grade lymphomas, and all high-grade lymphomas were 4F2 positive. Similarly, the mean intensity of 4F2 antigen expression increased with higher grade. However, for certain histologic subtypes, 4F2 antigen expression did not correlate with morphologic grade. For example, in the intermediate-grade category less than one half of diffuse small cleaved cell lymphomas were 4F2 positive, and expression was weak, similar to that of low-grade lymphomas. In contrast, all other histologic subtypes of lymphoma in the intermediate-grade category were strongly 4F2 positive. Expression of 4F2 antigen also correlated with plasmacytoid differentiation. Seventy-three percent of plasmacytoid small lymphocytic lymphomas (compared with 31% of cases of non-plasmacytoid small lymphocytic lymphoma/chronic lymphocytic leukemia) and all plasma cell neoplasms expressed the 4F2 antigen, the latter cases strongly.     

Regulation of TCL1 expression in B- and T-cell lymphomas and reactive lymphoid tissues

Chromosomal rearrangements observed in T-cell prolymphocytic leukemia involve the translocation of one T-cell receptor gene to either chromosome 14q32 or Xq28, deregulating the expression of cellular protooncogenes of unknown function, such as TCL1 or its homologue, MTCP1. In the human hematopoietic system, TCL1 expression is predominantly observed in developing B lymphocytes, whereas its overexpression in T cells causes mature T-cell proliferation in transgenic mice. In this study, using a newly generated monoclonal antibody against recombinant TCL1 protein, we extended our analysis mainly by immunohistochemistry and also by fluorescence-activated cell sorting and Western blot to a large tumor lymphoma data bank including 194 cases of lymphoproliferative disorders of B- and T-cell origin as well as reactive lymphoid tissues. The results obtained show that in reactive lymphoid tissues, TCL1 is strongly expressed by a subset of mantle zone B lymphocytes and is expressed to a lesser extent by follicle center cells and by scattered interfollicular small lymphocytes. In B-cell neoplasia, TCL1 was expressed in the majority of the cases, including lymphoblastic lymphoma, chronic lymphocytic leukemia, mantle cell lymphoma, follicular lymphoma, Burkitt lymphoma, diffuse large B-cell lymphoma (60%), and primary cutaneous B cell lymphoma (55%). TCL1 expression was observed in both the cytoplasmic and nuclear compartments, as confirmed by Western blot analysis. Conversely, TCL1 was not expressed in Hodgkin/Reed-Sternberg cells, multiple myelomas, marginal zone B-cell lymphomas, CD30+ anaplastic large cell lymphoma, lymphoblastic T-cell lymphoma, peripheral T-cell lymphoma, and mycosis fungoides. These data indicate that TCL1 is expressed in more differentiated B cells, under both reactive and neoplastic conditions, from antigen committed B cells and in germinal center B cells and is down-regulated in the latest stage of B-cell differentiation.     

Global Histone Modification Profiles are Well Conserved Between Normal B Lymphocytes and Neoplastic Counterparts

The identification of cell type is essential in diagnostic tumor histopathology. We hypothesized that some patterns of global histone modification are specific to both particular cell types of non-neoplastic tissues and their neoplastic counterparts. To examine the hypothesis in lymphoid cells, global histone modification patterns of germinal center and mantle zone B cells in reactive lymphoid hyperplasia (RLH) were compared with those of follicular lymphoma (FL) and mantle cell lymphoma (MTL) cells by immunohistochemistry. We revealed that FL cells and MTL cells exhibited the similar histone modification pattern to that of germinal center B lymphocytes and mantle zone B lymphocytes in RLH, respectively. These results indicate that global histone modification profiles specific to non-neoplastic germinal center B lymphocytes and mantle zone B lymphocytes are well conserved in corresponding neoplastic lymphoma cells, and suggest that they will be indicative of tumor cell type at least in B cell lymphoma.     

Practical Utility of the Revised European-American Classification of Lymphoid Neoplasms for Japanese Non-Hodgkin's Lymphomas

A clinicopathological study of 515 non-Hodgkin's lymphoma (NHL) cases was performed using the revised European-American classification of lymphoid neoplasms (REAL classification) in an HTLV1-nonendemic area of Japan. The following characteristics were revealed: 1) frequency of extranodal lymphomas was high (59%) with 79% B-cell lymphomas in this series, while the overall ratio of B:T/NK lineage was 3.7:1; 2) the most common type was the diffuse large B-cell lymphoma (46%), follicle center lymphomas occurred at an incidence lower (15%) than that in European and American populations, and marginal zone B-cell lymphomas accounted for as much as 12%; 3) peripheral T-cell lymphomas were common (19%), with the unspecified type predominant (11%), while adult T-cell lymphomas were present at a level equivalent to that among European and American patients (1%). Clear segregation of survival curves was rated according to cell lineage and B-cell lymphomas had a better prognosis than T/NK-cell lymphomas. Furthermore, new subtypes in the REAL classification, such as marginal zone B-cell and mantle cell lymphomas, exhibited distinct curves. Taken altogether, the REAL classification demonstrated advantages for assessment of Japanese NHL cases.     

Molecular heterogeneity of splenic marginal zone lymphomas: analysis of mutations in the 5' non-coding region of the bcl-6 gene.

Splenic marginal zone lymphoma (SMZL) has been recognized as a distinctive type of small B cell lymphoma, and defined on the basis of its morphological, phenotypic, clinical and molecular characteristics. In spite of this, the borders of the entity, the homogeneity of the cases and the presumably cell origin of SMZL remain controversial issues. The frequency of mutation in the 5' non-coding region of the bcl-6 gene has been used as a marker of germinal center derivation, which may be used to establish the molecular heterogeneity of different non-Hodgkin lymphoma (NHL) types. This roughly parallels the characteristics and frequency of the somatic hypermutations found in the immunoglobulin heavy chain variable region (IgVH) genes. This study analyzed mutations of bcl-6 in the 5' non-coding region in 22 SMZL cases and, for the purpose of comparison with different B cell subsets, in microdissected germinal centers, mantle zones and marginal zone subpopulations from reactive splenic lymphoid follicles. A majority of the SMZL cases studied, 19/22 (87%), bear unmutated bcl-6 gene, while mutation was only observed in 3/22 (13%) cases. Analysis of normal B cell subpopulations showed bcl-6 hypermutation in 3/10 (30%) germinal center clones, 5/14 (35%) marginal zone clones; and unmutated sequences in all clones derived from mantle cells. The frequency of these mutations in normal spleen confirms previous findings on the hypermutation IgVH process in normal B cell populations. The data presented here support the existence of molecular heterogeneity in this entity, and give additional results in favor of the hypothesis that, in spite of initial morphological observations, a significant proportion of SMZL cases could derive from an unmutated naive precursor, different from the marginal zone, and possibly located in the mantle zone of splenic lymphoid follicles. Thus the marginal zone differentiation of these tumors could be related more with the splenic microenvironment than it is to the histogenetic characteristics of the tumor.     

Heterogeneous in situ immunophenotyping of follicular dendritic reticulum cells in malignant lymphomas of B-cell origin

The phenotype of follicular dendritic reticulum cells (DRC) was analyzed with monoclonal antibodies (DRC-1, OKB7, BA-2, Leu-M3, and antidesmoplakin 1 and 2) in 28 frozen biopsy specimens of both morphologically and phenotypically analyzed B-cell lymphomas and 21 normal or reactive controls. The former included 15 follicular center cell lymphomas (FCCL), four intermediately differentiated lymphocytic lymphomas (ILL), four mantle zone lymphomas (MZL), and five well-differentiated lymphocytic lymphomas (WDLL). In controls, DRC-1+ and OKB7+ DRC were localized in both follicular centers (FC) and mantle zones (MZ), but BA-2+ and Leu-M3+ DRC were confined to FC only. FCCL were usually accompanied by DRC-1+, OKB7+, and BA-2+ DRC, and either lost or maintained positively with Leu-M3 from case to case. By contrast, MZL consistently lacked BA-2+ and Leu-M3+ DRC, and was associated with DRC-1+ and OKB7+ DRC only. Desmoplakin-positive DRC occurred in variable proportions in both FCCL and MZL. As opposed to FCCL and MZL, all WDLL and all but one of the ILL (associated only with DRC-1+, OKB7+, and desmoplakin+ DRC) did not show any DRC as identifiable with the antibody panel used. Remarkably, the difference in the distribution of BA-2+ and Leu-M3+ DRC in the normal FC and MZ appears to be maintained in their neoplastic counterparts (FCCL and MZL) also. Such a difference represents an example of the possible interactions between lymphoma cells of different phenotype and their microenvironment, as portrayed by phenotypically heterogeneous DRC.     

Practical utility of the revised European-American classification of lymphoid neoplasms for Japanese non-Hodgkin's lymphomas.

A clinicopathological study of 515 non-Hodgkin's lymphoma (NHL) cases was performed using the revised European-American classification of lymphoid neoplasms (REAL classification) in an HTLV1-nonendemic area of Japan. The following characteristics were revealed: 1) frequency of extranodal lymphomas was high (59%) with 79% B-cell lymphomas in this series, while the overall ratio of B:T/NK lineage was 3.7:1; 2) the most common type was the diffuse large B-cell lymphoma (46%), follicle center lymphomas occurred at an incidence lower (15%) than that in European and American populations, and marginal zone B-cell lymphomas accounted for as much as 12%; 3) peripheral T-cell lymphomas were common (19%), with the unspecified type predominant (11%), while adult T-cell lymphomas were present at a level equivalent to that among European and American patients (1%). Clear segregation of survival curves was rated according to cell lineage and B-cell lymphomas had a better prognosis than T / NK-cell lymphomas. Furthermore, new subtypes in the REAL classification, such as marginal zone B-cell and mantle cell lymphomas, exhibited distinct curves. Taken altogether, the REAL classification demonstrated advantages for assessment of Japanese NHL cases.     

Expression of the Class II and III Beta-tubulin in neoplastic and non-neoplastic lymphoid tissues.

Aim: Abnormal expression pattern ofBetatubulin isotypesmay provide a molecular rationalefor thebehaviour of lymphoma subtypes. The study assessed class II and III Beta-tubulin expression in non-neoplastic and neoplastic lymphoid tissues. Their differential expressions may have diagnostic implications and potential usefulness in the development of new tumour biomarkers.Methods& results: This cross-sectional study investigated class II and III Beta-tubulin expression in 304 neoplastic and 20 normal lymphoid tissues using qualitatively and semi-quantitatively immunohistochemistry. Class II Beta-tubulin was expressed in the germinal centre, mantle zone and interfollicular region of normal lymphoid tissues. Class III Beta-tubulin expression however was germinal centre restricted. Among lymphomas, Class II Beta-tubulin was expressed in 15/15 (100%) lymphoblastic lymphomas, 229/231 (99%) mature B cell lymphomas, 22/22 (100%) T/NK-cell lymphomas and 36/36(100%) classical Hodgkin lymphomas. Class III Beta-tubulin expression however was more selective, found mainly in classical Hodgkin lymphomas (34/36 (94%)). It was also expressed in 58/171(34%) DLBCL, 11/12 (92%) mantle cell lymphomas and 6/6 (100%) Burkitt lymphomas. Other mature B cell, T/NK cell lymphomas and precursor lymphoblastic lymphomas were usually negative.Conclusion:Class II Beta-tubulin shows ubiquitous expression in the neoplastic and non-neoplastic lymphoisd tissues. In contrast, Class III Beta-tubulin expression is germinal centre-restricted. Its consistent expression in classical Hodgkin lymphoma is useful in the identification of Reed-Sternberg and Hodgkin cells. Its expression in a proportion of DLBCL, Burkitt and mantle cell lymphomas is of interest as this may be related to their aggressiveness.     

The expression of the peripheral cannabinoid receptor on cells of the immune system and non-Hodgkin's lymphomas

The peripheral cannabinoid receptor CB2 is expressed highly on normal human B-lymphocytes. C-terminal specific anti-CB2 antibody recognises a non-phosphorylated inactive receptor on na?ve and resting B-lymphocytes. Another, N-terminal specific CB2 antibody, primarily recognises B-cells present in the germinal centres of secondary follicles in lymph nodes. We hypothesise that N-terminal specific CB2 antibody recognises activated CB2 receptors. In this study, we showed using these antibodies, that expression of CB2 is generally absent on T-lymphocytes in reactive, non-malignant human lymphoid tissues. Applying single and dual immunohistochemistry, CD23(+) follicular dendritic cells and a small but significant subpopulation of CD68(+) macrophages showed positive staining with the N-terminal specific CB2 antibody but not with the C-terminal specific CB2 antibody. This may indicate the presence of an active CB2 receptor on these cells with possible involvement in immunomodulation. In contrast to the low expression on normal T-cells, abundant levels of CB2 protein were present on T-non-Hodgkin's lymphomas (NHL). Moreover, in many B-NHL, high CB2 protein expression was found as well. In contrast to the distinct expression patterns in normal immune tissues using the two different CB2 antibodies, NHL specimens in general stained positively with both. We conclude that CB2 receptor expression pattern may be abnormal in NHL.     

Insights into the multistep transformation process of lymphomas: IgH-associated translocations and tumor suppressor gene mutations in clonally related composite Hodgkin's and non-Hodgkin's lymphomas.

Clonally related composite lymphomas of Hodgkin's lymphoma (HL) and Non-Hodgkin's lymphoma (NHL) represent models to study the multistep transformation process in tumorigenesis and the development of two distinct tumors from a shared precursor. We analyzed six such lymphomas for transforming events. The HLs were combined in two cases with follicular lymphoma (FL), and in one case each with B-cell chronic lymphocytic leukemia, splenic marginal zone lymphoma, mantle cell lymphoma (MCL) and diffuse large B-cell lymphoma (DLBCL). In the HL/FL and HL/MCL combinations, BCL2/IGH and CCND1/IGH translocations, respectively, were detected in both the HL and NHL. No mutations were found in the tumor suppressor genes FAS, NFKBIA and ATM. The HL/DLBCL case harbored clonal replacement mutations of the TP53 gene on both alleles exclusively in the DLBCL. In conclusion, we present the first examples of molecularly verified IgH-associated translocations in HL, which also show that BCL2/IGH or CCND1/IGH translocations can represent early steps in the pathogenesis of composite HL/FL or HL/MCL. The restriction of the TP53 mutations to the DLBCL in the HL/DLBCL case exemplifies a late transforming event that presumably happened in the germinal center and affected the fate of a common lymphoma precursor cell towards development of a DLBCL.     

Kinase group protooncogenes in non-hodgkins-lymphomas and nonmalignant lymphoid-tissues - analysis of their expression by insitu hybridization assays

Expression of src related proto-oncogenes in non-Hodgkin's lymphomas and non-malignant lymph nodes was analyzed by means of in situ hybridization assays with biotinylated DNA probes. In 36 cases of non-Hodgkin's lymphomas, both c-mos and c-abl were expressed in 27 cases, and c-erbB and c-src were expressed in 15 cases and 7 cases, respectively. No case expressed c-fps or c-yes. On the contrary, in 11 cases of non-malignant lymph nodes c-erbB and c-mos was expressed in only 3 cases. No other proto-oncogenes were expressed. Lymphomas in general express multiple proto-oncogenes simultaneously. A variety of combinations of expressed proto-oncogenes were observed suggesting diversity among non-Hodgkin's lymphomas in biological characteristics. However, a clear association with the expression of a single proto-oncogene or the number of expressed proto-oncogenes with T cell / B cell types, or the histopathological classification of NHL, or disease prognosis was not observed.     

A novel methionine aminopeptidase-2 inhibitor, PPI-2458, inhibits non-Hodgkin's lymphoma cell proliferation in vitro and in vivo.

PURPOSE: Fumagillin and related compounds have potent antiproliferative activity through inhibition of methionine aminopeptidase-2 (MetAP-2). It has recently been reported that MetAP-2 is highly expressed in germinal center B cells and germinal center-derived non-Hodgkin's lymphomas (NHL), suggesting an important role for MetAP-2 in proliferating B cells. Therefore, we determined the importance of MetAP-2 in normal and transformed germinal center B cells by evaluating the effects of MetAP-2 inhibition on the form and function of germinal centers and germinal center-derived NHL cells. EXPERIMENTAL DESIGN: To examine the activity of PPI-2458 on germinal center morphology, spleen sections from cynomolgus monkeys treated with oral PPI-2458 were analyzed. Antiproliferative activity of PPI-2458 was assessed on germinal center-derived NHL lines in culture. A MetAP-2 pharmacodynamic assay was used to determine cellular MetAP-2 inhibition following PPI-2458 treatment. Finally, inhibition of MetAP-2 and proliferation by PPI-2458 was examined in the human SR NHL line in culture and in implanted xenografts. RESULTS: Oral PPI-2458 caused a reduction in germinal center size and number in lymphoid tissues from treated animals. PPI-2458 potently inhibited growth (GI(50) = 0.2-1.9 nmol/L) of several NHL lines in a manner that correlated with MetAP-2 inhibition. Moreover, orally administered PPI-2458 significantly inhibited SR tumor growth, which correlated with inhibition of tumor MetAP-2 (>85% at 100 mg/kg) in mice. CONCLUSIONS: These results show the potent antiproliferative activity of PPI-2458 on NHL lines in vitro and oral antitumor activity in vivo and suggest the therapeutic potential of PPI-2458 as a novel agent for treatment of NHL should be evaluated in the clinical setting.     

Mantle-zone lymphoma. An immunohistologic study

Mantle-zone lymphoma (MZL) is a histologically distinctive variant of follicular lymphocytic lymphoma which is characterized by a proliferation of atypical small lymphoid cells as wide mantles around benign-appearing germinal centers. Immunoperoxidase stains were performed on fixed and processed lymph nodes from four patients with MZL. Three cases were of the intermediate lymphocytic type, and one was of the small cleaved lymphocytic type. In all cases, the small lymphoid cells of the mantle zones did not stain. A monoclonal population (IgM, lambda) of plasma cells and large lymphoid cells was demonstrated predominantly in the paracortical areas in one case. In all cases, small numbers of plasma cells and large lymphoid cells in the follicle centers stained in a polyclonal pattern, confirming the benign nature of the centers. These findings suggest that follicular lymphomas of the mantle-zone type are exceptions to the theory that follicular B-cell lymphomas are derived from follicular center cells. Apparently, the lymphoid cells of MZL home to the mantle zones of secondary follicles, where they surround, proliferate, and eventually obliterate residual benign germinal centers.     

Immunohistochemical localization of adenosine deaminase in human benign extrathymic lymphoid tissues and B-cell lymphomas

Immunomorphologic methods were utilized to localize adenosine deaminase (ADA) in extrathymic benign lymphoid tissues and B-cell lymphomas. In reactive lymph nodes, tonsils and appendix, germinal centers displayed strong ADA-positive nuclear staining in small cleaved lymphocytes and weak nuclear and/or cytoplasmic staining in large lymphoid cells. A significant proportion of ADA-positive lymphocytes in the germinal centers were B-cells. The mantle zone of secondary follicles did not stain for ADA. The plasma cells in the medullary cords demonstrated mainly cytoplasmic staining. In the spleen, ADA-positive lymphocytes were located in the periarteriolar sheath and paratrabecular white pulp. In lymphoma B-cells, patterns of ADA staining were similar to those observed in normal B-lymphocytes of similar morphology. This study demonstrated that human normal and lymphoma B-lymphoid cells are heterogeneous with respect to ADA expression. This heterogeneity appears to be associated with differentiation and/or proliferation of B-lymphocytes.     

Follicle center lymphoma is associated with significantly elevated levels of BCL-6 expression among lymphoma subtypes, independent of chromosome 3q27 rearrangements.

The BCL-6 gene, located on chromosome 3q27, is implicated in the normal germinal center formation and is frequently rearranged in a wide spectrum of lymphomas. However the links between genetic alterations and expression of the gene are not clearly determined. We established a quantitative RT-PCR assay based on TaqMan technology to quantify BCL-6 mRNA expression in different subtypes of lymphomas and to compare the level of expression in lymphomas characterized by the presence or absence of BCL-6 translocation. Total RNA was extracted from 105 nodes biopsies (35 diffuse large B cell lymphomas (DLBCL); 26 follicle center lymphomas (FCL); 7 marginal zone lymphomas (MZL); 6 mantle cell lymphomas (MCL); 6 chronic lymphocytic leukemia (CLL); 5 T cell lymphomas (TCL); 7 classical Hodgkin diseases (HD); 6 nodal metastasis (NM); and 7 reactive hyperplasia (RH)). BCL-6 gene rearrangement was assessed by Southern blot analysis in 75% of 3q27(+) DLBCL (n = 20) cases and 67% of 3q27(+) cases (n = 10). The highest level of relative BCL-6 expression was observed in FCL (9.12 +/- 7.28) comparatively to the other lymphoma subtypes including DLBCL (2.53 +/- 1.82; P < 0.001), MCL (1.23 +/- 0.73), MZL (1.49 +/- 1.3), HD (1.60 +/- 1.00), TCL (1.75 +/- 1.64), but also RH (3.91 +/- 3.12) or NM (1.95 +/- 2.6). Among the 26 FCL cases, we observed a lower expression in grade 3 (n = 8) than in grade 1/2 (P < 0.001). Conversely, we failed to show any difference between 3q27(+) DLBCL and 3q27(-)DLBCL cases (P = 0.42). Paradoxically BCL-6 expression in 3q27(+) FCL (n = 10) was significantly lower than in 3q27(-) FCL cases (P = 0.035). Finally, this study showed that BCL-6 expression in lymphoma is largely independent of chromosome 3q27 rearrangement and is more related to the histological subtype. Clinical implication and alternative deregulation pathways of BCL-6 expression remain to be determined.