Early-stage diffuse large B cell lymphoma of the head and neck: clinico-biological characterization and 18 year follow-up of 488 patients (IELSG 23 study).

It is known that extranodal head and neck diffuse large B cell lymphomas (eHN-DLBCL) can affect various anatomical structures what is not well-known, however, is whether they differ in terms of clinical presentation and outcome. Clinical data of the multi-institutional series, the largest of its kind as yet, has been analysed with the aim of answering these open questions and providing long-term follow-up information. Data from 488 patients affected by stage I/II eHN-DLBCL was collected: 300 of the Waldeyer's Ring (WR), 38 of the parotid and salivary glands (PSG), 48 of the thyroid gland (TG), 53 of the nasal cavity and paranasal sinuses (NPS), 24 of the palate and oral cavity (POC) and 25 with more than one involved site. Different eHN-DLBCL arising have distinct characteristics at presentation. The intermediate high risk-modified IPI was 67 % in TG, 44 % in WR, 38 % in PSG and POC and 20 % in MS. The worst 5-year survival rate had TG-DLBCL (61 %) due to the 61 % of patients with a mIPI >1. The addition of radiotherapy (cRT) to remitters did not translate into a survival advantage (5-year disease-free survival of 67 % in the cRT group vs. 70 % in the other). Three of four central nervous system recurrences occurred in NPS-DLBCL. Survival of HN-DLBCL was inferior to nodal DLBCL. This study showed that eHN-DLBCL remitters have an inferior survival when compared to nodal DLBCL, and that the addition of cRT does not provide a survival advantage. Since the standard of care nowadays is chemo-immunotherapy, survival of these patients might have been improved.

Proliferation centers in chronic lymphocytic leukemia: correlation with cytogenetic and clinicobiological features in consecutive patients analyzed on tissue microarrays.

To better define the significance of proliferation centers (PCs), the morphological hallmark of chronic lymphocytic leukemia (CLL), lymph node biopsies taken from 183 patients were submitted to histopathologic and fluorescence in situ hybridization (FISH) studies using a 5-probe panel on tissue microarrays. Seventy-five cases (40.9%) with confluent PCs were classified as 'PCs-rich' and 108 cases (59.1%) with scattered PCs were classified as 'typical'. Complete FISH data were obtained in 101 cases (55.1%), 79 of which (78.2%) displayed at least one chromosomal aberration. The incidence of each aberration was: 13q- 36,7%, 14q32 translocations 30.8%, 11q- 24.7%, trisomy 12 19.5% and 17p- 15.6%. Five cases showed extra copies of the 14q32 region. The 'PCs-rich' group was associated with 17p-, 14q32/IgH translocation, +12, Ki-67>30%. The median survival from the time of tissue biopsy for PCs-rich and typical groups was 11 and 64 months, respectively (P=0.00001). The PCs-rich pattern was the only predictive factor of an inferior survival at multivariate analysis (P=0.022). These findings establish an association between cytogenetic profile and the amount of PC in CLL, and show that this histopathologic characteristic is of value for risk assessment in patients with clinically significant adenopathy.

Subcutaneous 'lipoma-like' B-cell lymphoma associated with HCV infection: a new presentation of primary extranodal marginal zone B-cell lymphoma of MALT.

BACKGROUND: Hepatitis C virus (HCV) infection has been linked to lymphoproliferative disorders. Marginal zone B-cell lymphoma (MZL) represents one of the most frequent lymphoma subtypes associated with HCV infection. We describe an unusual subset of HCV-associated MZL characterized by subcutaneous presentation. MATERIALS AND METHODS: A series of 12 HCV-positive patients presenting with subcutaneous nodules that revealed lymphoma infiltration at biopsy. Molecular analysis of immunoglobulin heavy chain (IGH) gene rearrangement and FISH investigations for t(11;18)(q21;q21) and t(14;18)(q32;q21) were carried out in nine patients. RESULTS: The 12 patients (median age 69.5 years), all with positive HCV serology, presented with single or multiple subcutaneous nodules resembling lipomas. Histologically the lesions showed lymphoid infiltrates, consistent with extranodal MZL of mucosa-associated lymphoid tissue (MALT). Functional IGH gene rearrangements were identified in nine tested patients, with somatic mutations in 82%, indicating a histogenesis from germinal center-experienced B cells. The t(11;18) was found in two of nine cases. Staging did not show any other lymphoma localization. In two patients, a response was achieved with antiviral treatment. Extracutaneous spread to MALT sites occurred in a case. CONCLUSIONS: Our observations expand the spectrum of HCV-associated lymphomas to include a subset of extranodal MZL characterized by a novel primary 'lipoma-like' subcutaneous presentation and indolent clinical course.

Analysis of the host pharmacogenetic background for prediction of outcome and toxicity in diffuse large B-cell lymphoma treated with R-CHOP21.

Knowledge on the impact of pharmacogenetics in predicting outcome and toxicity in diffuse large B-cell lymphoma (DLBCL) is scant. We tested 106 consecutive DLBCL treated with R-CHOP21 for 19 single nucleotide polymorphisms (SNPs) from 15 genes potentially relevant to rituximab-CHOP (R-CHOP) pharmacogenetics. Associations of SNPs with event-free survival (EFS) and toxicity were controlled for multiple testing. Genotypic variants of nicotinamide adenine dinucleotide phosphate (NAD(P)H) oxidase p22phox (CYBA rs4673) and alpha1 class glutathione S-transferase (GSTA1 rs3957357) were independent predictors of EFS (CYBA rs4673 TT genotype: HR 2.06, P=0.038; GSTA1 rs3957357 CT/TT genotypes: HR 0.38, P=0.003), after adjusting for International Prognostic Index (IPI). CYBA rs4673 and GSTA1 rs3957357 also predicted outcome in DLBCL subgroups by IPI. Impact of SNPs on toxicity was evaluated in 658 R-CHOP21 courses utilizing generalized estimating equations. NCF4 rs1883112 was an independent predictor against hematologic (odds ratios (OR): 0.45; P=0.018), infectious (OR: 0.46; P=0.003) and cardiac toxicity (OR: 0.37; P=0.023). Overall, host SNPs affecting doxorubicin pharmacodynamics (CYBA rs4673) and alkylator detoxification (GSTA1 rs3957357) may predict outcome in R-CHOP21-treated DLBCL. Also, NCF4 rs1883112, a SNP of NAD(P)H oxidase p40phox, may have a function in protecting against hematologic and nonhematologic toxicity. These results highlight the need to improve characterization of the host genetic background for a better prognostication of DLBCL.

Telomere length is an independent predictor of survival, treatment requirement and Richter's syndrome transformation in chronic lymphocytic leukemia.

Telomere length (TL) has been associated with outcome in chronic lymphocytic leukemia (CLL). The aim of this extensive analysis carried out on 401 CLL patients was to assess TL conclusively as a prognostic biomarker. Our study included two cohorts used as learning (191 patients) and blinded validation series (210 patients). A TL cutoff of 5000 bp was chosen by receiver operating characteristic (ROC) analysis and Youden's index in the learning series. In this series, TL< or =5000 bp was independently associated to a worse outcome for both overall survival (OS; 105.5 vs 281 months, P<0.001) and treatment-free survival (TFS; 24.6 vs 73 months, P<0.001). In the blinded validation series, TL< or =5000 bp was confirmed as an independent outcome predictor for OS (79.8 vs not reached, P<0.001) and TFS (15.2 vs 130.8 months, P<0.001). Moreover, TL< or =5000 bp independently predicted the risk of Richter's syndrome (5-year risk: 18.9 vs 6.4%, P=0.016). Within CLL subsets defined by biological predictors, TL consistently identified patient subgroups harboring unfavorable prognosis. These results demonstrate that TL is a powerful independent predictor of multiple outcomes in CLL, and contributes to refine the prognostic assessment of this disease when utilized in combination with other prognostic markers. We thus believe that this prognostic biomarker has the potential for a more widespread use in CLL.

Evidence of biased immunoglobulin variable gene usage in highly stable B-cell chronic lymphocytic leukemia.

Recognition of biased immunoglobulin variable (IgV) gene usage in B-cell chronic lymphocytic leukemia (B-CLL) may yield insight into leukemogenesis and may help to refine prognostic categories. We explored Ig variable heavy (VH) and light (VL) chain gene usage in highly stable and indolent B-CLL (n=25) who never required treatment over 10 or more years. We observed an unexpectedly high usage of mutated VH3-72 (6/25; 24.0%), a gene that was otherwise rare in B-CLL (7/805; 0.87%; P<0.01), including mutated cases (6/432; 1.39%; P<0.01) and was exceptional among indolent (1/230, 0.435%; P<0.01), and aggressive B-cell lymphomas (0/105; P<0.01). Three of six VH3-72 B-CLL cases utilized the same VL Vkappa4-1 gene. Two V(H)3-72 B-CLL cases had highly homologous VH complementarity determining regions 3 (CDR3s), encoding Cys-XXXX-Cys domains, and utilized Vkappa4-1 genes with homologous IgVL CDR3s. An identical threonine to isoleucine change at codon 84 of V(H)3-72 framework region 3 (FR3) recurred in four cases of highly stable VH3-72 B-CLL. This mutation is expected to cause a conformational change of FR3 proximal to CDR3 that might critically affect high-affinity antigen binding. B-cell receptors encoded by VH3-72 may identify a specific B-CLL group and be implicated in leukemogenesis through an antigen-driven expansion of B cells.

Post-transplant lymphoproliferative disorders. Molecular analysis of histogenesis and pathogenesis.

AIM: Post-transplant lymphoproliferative disorders (PTLD) represent a serious complication of solid organ transplantation. Despite several advances in the biological categorization of PTLD, current classifications are not fully predictive of the clinical behavior of the disease. This study assessed a comprehensive molecular analysis of the clinico-pathologic spectrum of PTLD in order to better clarify the physiopathology of these disorders. METHODS: Fifty-two monoclonal PTLD were investigated for: 1). somatic hypermutation of IgV genes by direct sequencing of IgV rearrangements; 2). expression of BCL6, MUM1 and CD138 proteins by immunohistochemistry; 3). aberrant hypermethylation of DAP-kinase gene by methylation-specific polymerase chain reaction (PCR); 4). genotypic characterization of Epstein Barr virus (EBV) in EBV infected PTLD by PCR analysis of the prevalence of deletions in the carboxyterminal portion of the LMP1 gene and for the definition of type-1/type-2 EBV infection. RESULTS: We report that virtually all monoclonal PTLD originate from B cells that have experienced the germinal center (GC) reaction reflecting different stages of mature B cell differentiation and that tumor development seems frequently associated with EBV and/or other molecular lesions preventing apoptosis of cells that have failed the physiological process of germinal center reaction. CONCLUSION: To date, classification of PTLD is mainly based on morphology and conventional immunophenotyping. Because current classification schemes are not fully predictive of prognosis, knowledge of PTLD histogenesis and pathogenesis may potentially contribute to refine the distinction of PTLD into more homogeneous categories with prognostic relevance.

Point mutations of the BCL-6 gene: clinical and prognostic correlation in B-diffuse large cell lymphoma.

Although point mutations of the 5' noncoding regions of the BCL-6 proto-oncogene are frequently detected in B-diffuse large cell lymphoma (B-DLCL), a thorough analysis of the clinical correlation of these mutations has not been performed to date. In this study, BCL-6 mutations were examined by DNA direct sequencing in 103 patients with B-DLCL. BCL-6 mutations were found in 53/103 patients, including 38/76 treated with standard chemotherapy and 15/27 treated with autologous stem cell transplantation (ASCT) up front. The presence of BCL-6 mutations was correlated with clinical features at diagnosis and outcome. Mutated patients had a significantly higher LDH level (66% vs 38%, P < 0.05), and bulky disease (51% vs 32%, P = 0.05). In the whole series of patients BCL-6 mutations did not affect CR and OS. Patients with BCL-6 mutations tended to have a prolonged 5-years DFS and FFS compared to those without mutations (DFS 82% vs 63%, FFS 63% vs 49%). Among B-DLCL treated with standard chemotherapy, mutated patients showed a significantly improved 5-year DFS (85% vs 61%, P < 0.05) and, notably, the only four relapses observed among mutated patients occurred in less than 8 months. The multivariate regression analysis (P < 0.01) with DFS as endpoint confirmed the independent prognostic value of BCL-6 mutations. There was a trend for 5-year failure-free survival to be better for patients with BCL-6 mutations (63% vs 43%, P = 0.09). In the 27 patients treated with ASCT, BCL-6 mutations did not correlate with outcome. These results suggest that BCL-6 mutations may predict a higher chance of being free of disease in B-DLCL treated with standard chemotherapy. Larger series of patients need to be analyzed to evaluate the clinical relevance of BCL-6 mutations properly.

Genetic pathways and histogenetic models of AIDS-related lymphomas.

Acquired immunodeficiency syndrome (AIDS)-related lymphomas consistently display a B-cell phenotype and are histogenetically related to germinal centre or post-germinal centre B cells in the overwhelming majority of cases. The pathogenesis of AIDS-related lymphoma is a multistep process involving factors provided by the host as well as alterations intrinsic to the tumour clone. The molecular pathways of viral infection and lesions of cancer-related genes associated with AIDS-related lymphomas vary substantially in different clinicopathological categories of the disease and highlight the marked degree of biological heterogeneity of these lymphomas.

Expression profile of MUM1/IRF4, BCL-6, and CD138/syndecan-1 defines novel histogenetic subsets of human immunodeficiency virus-related lymphomas.

This study was aimed at defining the histogenesis of the pathologic spectrum of lymphoma arising in the context of human immunodeficiency virus (HIV) infection. Toward this aim, 87 AIDS-related non-Hodgkin lymphomas (AIDS-NHL) and 16 Hodgkin lymphomas arising in HIV+ patients (HIV-HL) were comparatively analyzed for the expression pattern of several B-cell histogenetic markers, including BCL-6 (expressed by centroblasts and centrocytes), MUM1/IRF4 (expressed by late centrocytes and post-germinal center [GC] B cells), and CD138/syn-1 (expressed by post-GC B cells). Expression of MUM1, BCL-6, and syn-1 segregated 3 major phenotypic patterns among AIDS-NHL and HIV-HL: (1) the BCL-6+/MUM1-/syn-1- pattern, selectively clustering with a large fraction of AIDS-Burkitt lymphoma (17 of 19) and of systemic AIDS-diffuse large cell lymphoma (12 of 16); (2) the BCL-6-/MUM1+/syn-1- pattern, associated with a fraction of AIDS-immunoblastic lymphoma (8 of 24); and (3) the BCL-6-/MUM1+/syn-1+ pattern, associated with systemic and primary central nervous system immunoblastic lymphoma (14 of 24) and with primary effusion lymphoma (10 of 10), plasmablastic lymphoma of the oral cavity (7 of 7), and HIV-HL (15 of 16). Analysis of nonneoplastic lymph nodes showed that the 3 phenotypic patterns detected in AIDS-NHL and HIV-HL correspond to distinct stages of physiologic B-cell development-centroblasts (BCL-6+/MUM1-/syn-1-), late GC/early post-GC B cells (BCL-6-/MUM1+/syn-1-), and post-GC B cells (BCL-6-/MUM1+/syn-1+). Expression of the Epstein-Barr virus-encoded latent membrane protein-1 clustered with the BCL-6-/MUM1+/syn-1+ profile throughout the clinicopathologic spectrum of AIDS-NHL and HIV-HL. Overall, these results define novel histogenetic subsets of AIDS-NHL and HIV-HL and may provide novel tools for refining the diagnosis of these disorders.

Expression of MUM1/IRF4 selectively clusters with primary effusion lymphoma among lymphomatous effusions: implications for disease histogenesis and pathogenesis.

Primary effusion lymphoma (PEL) is a peculiar B-cell lymphoma characterized by infection by human herpesvirus type-8/Kaposi sarcoma-associated herpesvirus (HHV-8/KSHV) and by preferential growth in the serous body cavities. Histogenetic studies have suggested that PEL originates from B cells at a late stage of differentiation. In this study, we have investigated PEL for the expression status of MUM1/IRF4 (multiple myeloma 1/interferon regulatory factor 4) protein, which is involved in physiological B-cell maturation and represents a histogenetic marker of late B-cell differentiation. Using multiple detection assays, all cases of PEL (n = 22) were found to express MUM1/IRF4 molecules. MUM1/IRF4 expression was a selective feature of PEL among lymphomas involving the serous body cavities as secondary lymphomatous effusions generally failed to express the protein. In reactive lymphoid tissues, MUM1/ IRF4 expression clustered with advanced stages of B-cell differentiation. Comparison of MUM1/IRF4 expression with that of other histogenetic markers defined two phenotypic variants of PEL, i.e. MUM1/IRF4+, CD138/syndecan-1+, B-cell antigen- (20 out of 22 cases) and MUM1/IRF4+, CD138/syndecan-1-, B-cell antigen+ (2 out of 22 cases), suggesting a certain degree of heterogeneity in the disease histogenesis. The implications of these data are threefold. First, MUM1/IRF4 expression corroborates the notion that PEL originates from post-germinal centre, preterminally differentiated B-cells. Second, MUM1/IRF4 may help in the differential diagnosis of PEL among other lymphomas involving the serous body cavities. Finally, MUM1/IRF4 may interact with HHV-8/KSHV-encoded interferon regulatory factors (IRFs) and thus contribute to PEL escape from interferon-mediated control of viral infection.

Occurrence of multiple myeloma after fludarabine treatment of a chronic lymphocytic leukemia: evidence of a biclonal derivation and clinical response to autologous stem cell transplantation.

BACKGROUND AND OBJECTIVES: The occurrence of chronic lymphocyte leukemia (CLL) and multiple myeloma (MM) in a single individual is rare and there is no consensus about the clonal relationship of the two disorders and no clinical data about the response to therapy. DESIGN AND METHODS: We describe a 49-year old patient who developed a III stage IgD k MM after fludarabine treatment for a previous diagnosis of CLL and then was submitted to an high-dose treatment with autologous CD34+ selected stem cell support. An immunologic and molecular characterisation of peripheral blood and bone marrow was performed at the time of appearance of the two coexisting neoplasms. RESULTS: By immunophenotyping, monoclonal B-lymphocytes stained with l chains, whereas marrow plasma cells were positive for k chains. The Ig heavy chain rearrangement analysis performed on the bone marrow confirmed the presence of two distinct tumour clones, one of which was also present in the peripheral blood. During an 18 months follow-up after autotransplantation, the CLL-related clone became undetectable, whereas MM persisted with a minimal amount of Bence Jones proteinuria and a 15-20% plasma cell marrow infiltration. INTERPRETATION AND CONCLUSIONS: Our results suggest that in this patient CLL and MM originate from separate B-cell progenitors. Both disorders were responsive to a CD34+ selected ASCT.

The role of cytokines in the pathogenesis and management of AIDS-related lymphomas.

AIDS-related non-Hodgkin lymphomas (AIDS-NHL) consistently derive from B-cells and are characterized by extreme clinical aggressiveness. At histological level, AIDS-NHL are classified as AIDS-related Burkitt's lymphoma (AIDS-BL), AIDS-related diffuse large cell lymphoma (AIDS-DLCL) and AIDS-related primary effusion lymphoma (AIDS-PEL). The role of cytokines in the pathogenesis and management of AIDS-NHL has been studied to a certain extent. Production of large quantities of human IL-10 occurs frequently in AIDS-BL and correlates with latent EBV infection of the tumor clone. Lesser amounts of the cytokine are released in EBV negative cases. The pathogenetic role of IL-10 in AIDS-BL is suggested by the observation that IL-10 antisense oligonucleotides inhibit proliferation of the lymphoma. A significant fraction of AIDS-BL cell lines produce TNFbeta. Among AIDS-NHL, the release of TNFbeta appears to be specific for AIDS-BL. The pathogenetic relevance of TNFbeta in lymphomagenesis is suggested by the observation that some BL cell lines use TNFbeta as an autocrine growth factor. Some cases of AIDS-BL, particularly those carrying EBV infection, also secrete IL-6, IL-7 and IL-12. With respect to AIDS-DLCL, many cases express the IL-6R, rendering these cells responsive to the paracrine stimulation by the IL-6 produced by nearby T-cells, macrophages and endothelial cells which are frequently abundant in these tumor samples. The tumor clone itself, however, generally fails to release IL-6. AIDS-PEL is characterized by secretion of large amounts of IL-6 and IL-10. Some PEL cases also release oncostatin M. Apart from human IL-6, PEL also express viral IL-6, which is encoded by the HHV-8 genome. The biological relevance of both IL-6 and IL-10 in PEL proliferation and growth has been recently clarified in vitro and in vivo. Overall, these data suggest that activation of different cytokine loops clusters with different clinico-pathologic categories of AIDS-NHL and may represent the potential target of novel therapeutic strategies.

The molecular basis of acquired immunodeficiency syndrome-related lymphomagenesis.

Acquired immunodeficiency syndrome (AIDS)-related lymphomas consistently display a B-cell phenotype and are histogenetically related to germinal center (GC) or post-GC B cells in the overwhelming majority of cases. The pathogenesis of AIDS-related lymphoma is a multistep process involving factors provided by the host, as well as alterations intrinsic to the tumor one. Host factors involved in AIDS-related lymphomagenesis include reduced immunosurveillance particularly against Epstein-Barr virus (EBV)-infected B cells, human immunodeficiency virus (HIV)-induced alteration of endothelial functions, B-cell stimulation and selection by antigen, HIV-induced deregulation of several cytokine loops, and possibly the host's genetic background. The molecular pathways of viral infection and lesions of cancer related genes associated with AIDS-related lymphoma vary substantially in different clinicopathologic categories of the disease and highlight the marked degree of biological heterogeneity of these lymphomas. Although the reasons for the heterogeneity of AIDS-related lymphoma are not totally clear, it is generally believed that the host's background selects for which specific molecular pathway of AIDS-related lymphoma is activated in a given patient.

Common-variable immunodeficiency-related lymphomas associate with mutations and rearrangements of BCL-6: pathogenetic and histogenetic implications.

Common-variable immunodeficiency (CVI) patients develop non-Hodgkin's lymphomas (NHL), mainly B-lineage diffuse large-cell lymphomas (DLCL), with a high relative risk. The molecular pathogenesis of CVI-related NHL (CVI-NHL) is unknown. Here we aimed at providing a detailed molecular characterization of CVI-NHL. Rearrangements of BCL-6 were detected in two thirds of CVI-NHL cases examined. All 3 CVI-NHL also harbored point mutations of the BCL-6 5' noncoding regions, which constitute a marker of B-cell transit through the germinal center (GC). The number and molecular pattern of BCL-6 mutations in CVI-NHL were similar to that detected in DLCL of immunocompetent hosts and in DLCL arising in other immunodeficiency settings. Microsatellite instability occurred in one CVI-NHL devoid of a BCL-6 rearrangement. All CVI-NHL scored negative for genetic lesions of BCL-2, p53, c-MYC, REL as well as for viral infection by EBV and HHV-8. Overall, these data indicate that: similarly to other immunodeficiency-related NHL, involvement of BCL6 occurs frequently also in CVI-NHL; and because BCL-6 mutations are acquired by B cells during GC transit, their occurrence in CVI-NHL suggest that these lymphomas are histogenetically related to GC B cells.

Characterization of a novel HHV-8-positive cell line reveals implications for the pathogenesis and cell cycle control of primary effusion lymphoma.

Primary effusion lymphoma (PEL) represents a peculiar type of B cell lymphoma which associates with HHV-8 infection and preferentially grows in liquid phase in the serous body cavities. In this report, we provide the detailed characterization of a newly established PEL cell line, termed CRO-AP/6. The cell line was obtained from the pleural effusion of a HIV-positive patient with PEL. Its derivation from the tumor clone was established by immunogenotypic analysis. Detailed phenotypic investigations defined that CRO-AP/6 reflects pre-terminally differentiated B cells expressing the CD138/syndecan-1 antigen. Karyotypic studies of CRO-AP/6 identified several chromosomal abnormalities, whereas genotypic studies ruled out the involvement of molecular lesions associated with other types of B cell lymphoma. Both CRO-AP/6 and the parental tumor sample harbored infection by HHV-8. Conversely, EBV infection was present in the parental tumor sample although not in CROAP/6, indicating that CRO-AP/6 originated from the selection of an EBV-negative tumor subclone. The pattern of viral (HHV-8 v-cyclin) and cellular (p27Kip1) regulators of cell cycle expressed by CRO-AP/6, together with the results of growth fraction analysis, point to abrogation of the physiological inverse relationship between proliferation and p27Kip1 expression. Also, both CRO-AP/6 and the parental tumor sample display biallelic inactivation of the DNA repair enzyme gene O6-methylguanine-DNA methyltransferase (MGMT) by promoter methylation. Overall, the CRO-AP/6 cell line may help understand cell cycle control of PEL cells, may clarify the relative contribution of HHV-8 and EBV to the disease growth and development and may facilitate the identification of recurrent cytogenetic abnormalities highlighting putative novel cancer related loci relevant to PEL.

Identification of three subgroups of B cell chronic lymphocytic leukemia based upon mutations of BCL-6 and IgV genes.

Although B cell chronic lymphocytic leukemia (B-CLL) has been traditionally viewed as a tumor of virgin B cells, this notion has been recently questioned by data suggesting that a fraction of B-CLL derives from antigen experienced B cells. In order to further clarify the histogenetic derivation of this lymphoproliferation, we have analyzed the DNA sequences of the 5' non-coding region of BCL-6 proto-oncogene in 28 cases of B-CLL. Mutations of BCL-6 proto-oncogene, a zinc finger transcription factor implicated in lymphoma development, represent a histogenetic marker of B cell transit through the germinal center (GC) and occur frequently in B cell malignancies derived from GC or post-GC B cells. For comparison, the same tumor panel was analyzed for somatic mutations of the rearranged immunoglobulin variable (IgV) genes, which are known to be acquired at the time of B cell transit through the GC. Sequence analyses of BCL-6 and IgV genes allowed the definition of three groups of B-CLL. Group I B-CLL displayed mutations of both BCL-6 and IgV genes (10/28; 36%). Group II B-CLL displayed mutated IgV genes, but a germline BCL-6 gene (5/28; 18%). Finally, group III B-CLL included the remaining cases (13/28; 46%) that were characterized by the absence of somatic mutations of both BCL-6 and IgV genes. Overall, the distribution of BCL-6 and IgV mutations in B-CLL reinforce the notion that this leukemia is histogenetically heterogeneous and that a substantial subgroup of these lymphoproliferations derives from post-germinal center B cells.

Primary effusion lymphoma cell lines harbouring human herpesvirus type-8.

Primary effusion lymphoma (PEL) is a novel lymphoma entity consistently infected by HHV-8 that occurs predominantly in immunodeficient patients and is characterized by liquid growth in the serous body cavities. In order to facilitate the understanding of PEL pathogenesis and histogenesis, we have established three PEL cell lines termed CRO-AP/2, CRO-AP/3 and CRO-AP/5. All cell lines have been derived from HIV positive homosexual men affected by PEL with (in the case of CRO-AP/2 and CRO-AP/5) or without (in the case of CRO-AP/3) a previous history of Kaposi's sarcoma. The cell lines are representative of both virologic variants of PEL, i.e. HHV-8+ EBV+ PEL (CRO-AP/2 and CRO-AP/5) and HHV-8+ EBV- PEL (CRO-AP/3). Morphologic and phenotypic features of CRO-AP/2, CRO-AP/3 and CRO-AP/5 are typical of PEL, and include morphology bridging immunoblastic and anaplastic features as well as an indeterminate (non B- non T-cell) phenotype. The B-cell nature of the cell lines is documented by the presence of rearranged immunoglobulin genes. The detailed analysis of the molecular and phenotypic features of CRO-AP/2, CRO-AP/3 and CRO-AP/5 has allowed the identification of recurrent chromosomal abnormalities of PEL and has contributed to the definition of PEL as a lymphoma of post-germinal center, pre-terminally differentiated B-cells.