Homeostatic chemokines drive migration of malignant B cells in patients with non-Hodgkin lymphomas

This study investigated the role of several chemokines and their receptors on malignant B lymphocytes recovered from 13 patients with chronic lymphocytic leukemia (CLL), 9 with hairy cell leukemia (HCL), 5 with mantle cell lymphoma (MCL), 5 with marginal zone B-cell lymphoma (MZL), 6 with small lymphocytic lymphoma (SLL), and 5 with follicular cell lymphoma (FCL). Flow cytometry analysis demonstrated that CXCR4 and CXCR5 were expressed on all malignant and normal B cells. Considering CC receptors, CCR1 was expressed in 70% of patients with CLL and 40% of those with HCL but was lacking in patients with MCL, MZL, SLL, and normal B cells. CCR2 showed a heterogeneous pattern of expression. CCR3 was found in almost all patients with CLL and in the majority of those with HCL, whereas it was usually lacking in patients with MZL and SLL and in healthy subjects. CCR5 was expressed in patients with HCL and MCL. Migration assays showed that different chemokines, mainly CXCL12 and CXCL13, are able to trigger migration of malignant B lymphocytes. Some of these chemokines induce calcium mobilization. These data indicate that different patterns of chemokine receptor expression identify different malignant B-cell subsets and that these receptors are functional and might play a role in malignant B-cell circulation.     

Prohibitin expression is increased in phorbol ester-treated chronic leukemic B-lymphocytes

Chronic lymphocytic leukemia (CLL) is characterized by the gradual accumulation of immature B-lymphocytes. CLL B-lymphocytes mature to a plasmacytoid phenotype when treated in vitro with phorbol esters. CLL B-cell apparent maturation is associated with altered expression of specific plasma membrane and mitochondrial proteins including heightened expression of a 30-kDa heat shock protein 60 (hsp60) analog. During our efforts to further characterize this hsp60 analog by mass spectrometry, we detected the mitochondrial protein prohibitin in phorbol-ester-matured CLL B-lymphocytes. Prohibitin modulates cell proliferation and inhibits cell cycle traverse in several systems, although few data are available for lymphocytes. A twofold increase in prohibitin concentration was observed in phorbol-ester-matured compared to resting CLL B-cells as determined by quantitative Western immunoblot analysis. A similar increase in prohibitin was observed in phorbol-ester-treated normal human B-lymphocyte populations. An antisense oligonucleotide complementary to the 5' coding region of the prohibitin gene blunted the increase in prohibitin protein in phorbol-ester-treated CLL B-cells by 42%. These data suggest that increased prohibitin expression is associated with and may facilitate B-cell maturation.     

Quantitative flow cytometry for the differential diagnosis of leukemic B-cell chronic lymphoproliferative disorders

We have investigated whether the quantitative flow cytometry is an useful tool to better characterize B-cell chronic lymphoproliferative disorders (CLDs). Peripheral blood samples from 104 patients with leukemic B-cell disorders and 20 healthy donors were analyzed. Directly phycoerythrin-conjugated CD19, CD20, CD22, CD23, CD79b, and CD5 monoclonal antibodies (MoAbs) and QuantiBRITE pre-calibrated beads were used to calculate the number of antigen molecules per cell, expressed as antibody binding capacity (ABC). As compared to normal controls, in chronic lymphocytic leukemias (CLL) all MoAbs tested, with the exception of CD23 and CD5, showed lower ABC levels. In prolymphocytic leukemias (PL), CD5 and CD23 antigens were constantly absent while lower CD19 and CD22 ABC levels were observed. Hairy cell leukemias (HCL) displayed very high levels of CD20 and CD22. Of interest, splenic lymphomas with villous lymphocytes (SLVL) could be discriminated from HCL for higher CD79b and lower CD19 ABC values. Finally, higher CD20 levels were detected in follicular lymphomas (FL), whereas higher CD79b and CD5 levels characterized mantle cell lymphomas (MCL). Seven out of 61 CLL cases were defined as morphologically atypical. When compared with typical forms, lower levels of CD19 and CD23 and higher CD20 and CD22 ABC values were detected. However, we failed to demonstrate quantitative differences between atypical CLL and MCL. Our results suggest that quantitative flow cytometry may be a useful additional tool to better identify some types of B-cell CLDs.     

Towards molecular diagnosis and targeted therapy of lymphoid malignancies

Gene expression profiling of cancer began as a research tool but is rapidly moving towards clinical application. The diagnostic category of diffuse large B-cell lymphoma (DLBCL) can now be viewed as an amalgam of several different diseases that have distinct gene expression profiles, oncogenic mechanisms, and clinical outcomes. Other diagnostic categories such as chronic lymphocytic leukemia (CLL) have a single gene expression signature that distinguishes them from other lymphoid malignancies. Nevertheless, elevated expression of a single gene, ZAP-70, is characteristic of a more aggressive subtype of CLL that may require novel treatment approaches. In mantle cell lymphoma (MCL), a quantitative measurement of gene expression associated with tumor proliferation is a powerful predictor of survival. Ultimately, the molecular diagnosis of these malignancies will identify molecular pathways that can be exploited for therapy. For example, one of the gene expression subgroups of DLBCL, termed activated B-cell like DLBCL, is characterized by constitutive activation of the nuclear factor-kappaB (NF-kappaB) signaling pathway, and interference with this pathway selectively kills these lymphoma cells. The full benefit of gene expression profiling can only be realized if we incorporate this technology into prospective clinical trials.     

Chronic lymphocytic leukemia in Japan

Forty-one patients diagnosed as having B-cell chronic lymphocytic leukemia in Japan were evaluated. Patients were classified into five groups (CLL, CLL-L, CLL/PL, PLL, LSCL) according to differential counts of small lymphocytes, large lymphocytes, prolymphocytes, immunoblasts and/or lymphosarcoma cells among the lymphoid cells in the first available peripheral smears based on Melo's morphological criteria. Patients with typical CLL, defined as having more than 90% small lymphocytes, were seven (17%) of 41 patients. Phenotypical characteristic of CLL and its subgroups in Japan was considered to be the high expression of activated antigens, such as CD22, PCA1 and CD25. This finding may support the relatively higher proportion of atypical CLL with high percentage of large lymphocytes or prolymphocytes in Japan than that in Western countries. The molecular biological analysis revealed the deletion of C mu gene in one allele in three sIg-negative cases. The incidence of CLL, CLL-L and CLL/PL in Japan was deduced to be 1/10 of that in Western countries.     

Bcl-2 family of proteins in indolent B-cell non-Hodgkin's lymphoma: study of 116 cases

The bcl-2 family of proteins comprises both antagonists and agonists of apoptosis. We have investigated whether subsets of indolent B-cell non-Hodgkin's lymphoma (IB-NHL) differ in the expression of the bcl-2 family members; 116 cases of IB-NHL, composed of chronic lymphocytic leukemia (CLL, n = 48), follicular lymphoma (FL, n = 38), marginal zone B-cell lymphoma (MZBCL, n = 15), and mantle cell lymphoma (MCL, n = 15), were investigated for expression of bcl-2, bcl-X, mcl-1, bax, and bak proteins by immunohistochemistry. Expression of bcl-2 and bcl-X proteins was moderate/high among most IB-NHLs. Expression of mcl-1 was low/absent in most cases of CLL and MCL and low/moderate in most cases of FL and MZBCL. Most MCLs did not express bax protein. Bax expression was absent/low among most cases of CLL and low/moderate among most cases of FL and MZBCL. Expression of bak was moderate/low among most cases of CLL, MZBCL, and MCL but was absent/low among most cases of FL. The different subsets of IB-NHLs differ in their expression of mcl-1, bax, and bak proteins.     

Quantitative analysis of CD79b, CD5 and CD19 in mature B-cell lymphoproliferative disorders.

BACKGROUND AND OBJECTIVE: Distinction between B-cell chronic leukemias can be difficult due to overlap in cell morphology and immunologic features. We investigated, by quantitative flow cytometry, the expression of CD79b, CD5 and CD19 in cells from a variety of B-cell disorders to see whether this analysis adds further information useful to the diagnosis and characterization of these diseases. DESIGN AND METHODS: Peripheral blood cells from 6 normal individuals were used as reference controls. The diseases of the 63 patients investigated comprised: 29 chronic lymphocytic leukemia (CLL), six of them with atypical morphology, 6 B-cell prolymphocytic leukemia (PLL), 12 splenic lymphoma with villous lymphocytes (SLVL) and 16 mantle-cell (Mc) lymphoma in leukemic phase. The study was carried out by triple immunostaining with directly conjugated monoclonal antibodies (MoAb) against CD79b, CD5 and CD19 and quantitative estimation of the antigens per cell assessed with standard microbeads (Quantum Simply Cellular). RESULTS: Compared to normal B-cells, the number of CD19 molecules was significantly lower in cells from all of the B-cell disorders except PLL. The intensity of CD5 in leukemic B-cells was significantly higher in CLL cells, including atypical cases, and Mc lymphoma than in normal B-cells, whilst PLL and SLVL had values similar to those of normal B-lymphocytes. CD79b was expressed at lower levels in all types of leukemic cells compared to normal B-lymphocytes but differences were statistically significant in CLL, Mc lymphoma and SLVL. The number of CD79b molecules per cell was significantly lower in typical CLL than in the remaining B-cell diseases whilst the comparison of CD5 and CD19 intensity between CLL and non-CLL samples failed to show any statistically significant difference. INTERPRETATION AND CONCLUSIONS: Distinct antigen density patterns for the various conditions emerged from this analysis: Typical CLL was characterized by moderate CD5 and weak or negative CD79b expression. Mc lymphoma showed an homogeneous pattern, characterized by similar expression of CD5 than CLL but significantly stronger expression of CD79b whilst PLL and SLVL had weak CD5 and moderate CD79b expression. Atypical CLL had an intermediate pattern of CD79b antigen expression ranging from weak to moderate with bright CD5. Unlike CD5 and CD79b, CD19 did not discriminate the various B-cell disorders but only between normal and leukemic cells.     

Quantitative expression of CD23 and its ligand CD21 in chronic lymphocytic leukemia

BACKGROUND AND OBJECTIVES: Cells from the great majority of patients with chronic lymphocytic leukemia (CLL) express CD23. A recent histologic study has shown that CD23 is expressed more strongly in the proliferating centers of the lymph nodes, where the large prolymphocytoid cells are located. The aim of our study was to quantify the expression of CD23 and CD21 in small and prolymphocytoid cells from patients with CLL and B-cell lymphomas, and correlate this expression with clinical parameters. DESIGN AND METHODS: Using quantitative flow cyto-metry we analyzed the antigen density of CD23 and CD21 in: 1) 101 cases of chronic lymphocytic leukemia, 84 typical, 14 with increased prolymphocytes (CLL/PL) and 3 atypical, 2) 15 cases of CD23 positive B-cell lymphoma with circulating lymphoma cells and 3) 8 normal subjects. The results were correlated with morphology and clinical staging. RESULTS: Cells from CLL and CLL/PL have a significantly higher number of CD23 molecules than normal and lymphoma B-cells (p<0.001 and p<0.001, respectively). Differences were not significant for CD21. CLL and CLL/PL cases had similar values of CD23 and CD21 molecules, but analysis at a single level showed that prolymphocytes in typical CLL and CLL/PL expressed significantly higher CD23 (p=0.001, p=0.006) and CD21 (p=0.001, p=0.001) than small lymphocytes. There was no correlation between CD23 or CD21 antigen density and clinical stages although there was a trend for a brighter CD23 in stage C patients. INTERPRETATION AND CONCLUSIONS: Since interaction between CD23 and CD21 is important for B-cell activation, proliferation and tumor formation, findings that both molecules are upregulated in prolymphocytes suggest that this is the proliferating cell component in CLL and underline the association between progression and increased prolymphocytes in typical CLL and CLL/PL.     

Deletions at 11q23 in different lymphoma subtypes

BACKGROUND AND OBJECTIVES: Chromosome band 11q23 is frequently deleted in various types of neoplasm. The region represented by yeast artificial chromosome (YAC) clone 755b11 at 11q23 has been shown to be the minimal common region of deletion in mantle cell lymphoma (MCL) and B-cell chronic lymphocytic leukemia (B-CLL). The aim of the study was to determine the frequencies of 11q23 deletion in different lymphoma subtypes. DESIGN AND METHODS: We performed fluorescence in situ hybridization (FISH) analysis with YAC755b11 on either peripheral blood or lymph node biopsy (LN) specimens of patients diagnosed as having MCL (47), CLL/small lymphocytic lymphoma (SLL) (62), diffuse large cell lymphoma (DLCL) (17), follicular lymphoma (FL) (9), and Hodgkin's disease (HD) (11). Fifteen cases of reactive or normal lymph node biopsies were studied as controls. RESULTS: Forty of the 161 (25%) samples exhibited deletions in the region represented by YAC755b11. The 11q23 deletion was found only in MCL (23, 49%), CLL / SLL (13, 21%) and DLCL (4, 24%). Three cases were classified as Richter's syndrome and they all exhibited the deletion at 11q23. The deletion frequencies in the blood specimens of typical CLL (30%) and lymph node specimens of CLL/SLL (13%) were remarkably different. INTERPRETATION AND CONCLUSIONS: Our study demonstrated that the 11q23 deletion is not common in lymphomas other than MCL, CLL and DLCL. It also showed the possible correlation of the 11q23 deletion with the transformation of localized lymphoma to CLL, and with the development of Richter's syndrome.     

BCL-1 rearrangements and p53 mutations in atypical chronic lymphocytic leukemia with t(11;14)(q13;q32)

BACKGROUND AND OBJECTIVES: The translocation t(11;14) (q13;q32), typically described in mantle cell lymphomas (MCL), has also been found in some cases of non-MCL lymphoproliferative disorders, such as splenic lymphoma with villous lymphocytes (SLVL), multiple myeloma (MM), prolymphocytic leukemia (PLL), typical and atypical chronic lymphocytic leukemia (CLL and aCLL). In order to define better the genetic features of aCLL with t(11;14), which could represent a distinct disease subset, we looked for genetic lesions in the BCL-1 locus and in BCL-2, BCL-6, c-myc and p53 genes. DESIGN AND METHODS: We investigated a panel of B-lymphoproliferative disorders with translocation t(11;14)(q13;q32) including nine aCLL, six MCL and one MM. Southern and Northern blot analysis was used to investigate DNA structure and RNA expression; SSCP and direct sequencing were used to detect and characterize p53 point mutations; cytofluorimetric analysis was used to quantify p53 protein. RESULTS: Alterations of BCL-2, BCL-6 and c-myc were not detected. Conversely, BCL-1 rearrangements were present in 4 out of 7 aCLL and in 2 out of 4 MCL. A high incidence of p53 gene alterations was found, almost equivalent in aCLL and MCL. INTERPRETATION AND CONCLUSIONS: Our results indicate that the occurrence of BCL-1 locus lesions in aCLL selected for t(11;14) is as high as in MCL. Interestingly, rearrangements in the mTC1 (minor translocation cluster 1) were only found in aCLL. Therefore, the two B-cell chronic lymphoproliferative disorders share similar molecular rearrangements and the t(11;14) identifies a subset of B-CLL sharing molecular features with MCL and characterized by aggressive clinical evolution.     

Effective elimination of fludarabine-resistant CLL cells by PEITC through a redox-mediated mechanism

Chronic lymphocytic leukemia (CLL) is the most common adult leukemia, and resistance to fludarabine-based therapies is a major challenge in CLL treatment. Because CLL cells are known to have elevated levels of reactive oxygen species (ROS), we aimed to test a novel ROS-mediated strategy to eliminate fludarabine-resistant CLL cells based on this redox alteration. Using primary CLL cells and normal lymphocytes from patients (n = 58) and healthy subjects (n = 12), we showed that both fludarabine-resistant and -sensitive CLL cells were highly sensitive to beta-phenylethyl isothiocyanate (PEITC) with mean IC(50) values of 5.4 microM and 5.1 microM, respectively. Normal lymphocytes were significantly less sensitive to PEITC (IC(50) = 27 microM, P < .001). CLL cells exhibited intrinsically higher ROS level and lower cellular glutathione, which were shown to be the critical determinants of CLL sensitivity to PEITC. Exposure of CLL cells to PEITC induced severe glutathione depletion, ROS accumulation, and oxidation of mitochondrial cardiolipin leading to massive cell death. Such ROS stress also caused deglutathionylation of MCL1, followed by a rapid degradation of this cell survival molecule. Our study demonstrated that the natural compound PEITC is effective in eliminating fludarabine-resistant CLL cells through a redox-mediated mechanism with low toxicity to normal lymphocytes, and warrants further clinical evaluation.     

FCRL1 on chronic lymphocytic leukemia, hairy cell leukemia, and B-cell non-Hodgkin lymphoma as a target of immunotoxins

FCRL1 (Fc receptor-like 1) is a cell-surface membrane protein belonging to FCRL family and is preferentially expressed on B cells. To evaluate FcRL1 as an immunotherapy target for B-cell malignancies, we prepared anti-FCRL1 mAbs without cross-reactivity to other FCRL family proteins and analyzed FCRL1 protein expression on malignant cells from patients and on B-cell lines. Frequent FCRL1 expression was observed by flow cytometry on 12 B-cell non-Hodgkin lymphoma (B-NHL) cell lines and many patient samples: 12 of 14 chronic lymphocytic leukemia (CLL), 7 of 7 follicular lymphoma (FL), 13 of 17 hairy cell leukemia (HCL), and 2 of 3 mantle cell lymphoma (MCL). Two recombinant immunotoxins, E3(Fv)-PE38 and E9(Fv)-PE38, were constructed. Both immunotoxins bound to FCRL1-positive cells with similar affinities (3.4 and 3.2 nM) and were cytotoxic to cell lines, but E9(Fv)-PE38 was 4- to 20-fold more cytotoxic than E3(Fv)-PE38. The concentrations that inhibited response by 50% (IC(50)s) of E9(Fv)-PE38 on 11 different FCRL1-positive cell lines ranged from 1.0 ng/mL to 90 ng/mL and correlated with the FCRL1 expression levels. Our results suggest that anti-FCRL1 immunotoxin E9(Fv)-PE38 exhibits remarkably specific cytotoxicity and merits further evaluation for the treatment of FCRL1-positive malignancies, including CLL, HCL, FL, MCL, and other B-NHL.     

Splenic lymphoma with circulating villous lymphocytes/splenic marginal-zone lymphoma.

Splenic lymphoma with villous lymphocytes (SLVL) represents a low-grade B-cell non-Hodgkin's lymphoma (NHL) that histologically is indistinguishable from splenic marginal-zone lymphoma (SMZL). Characteristic features of SLVL are splenomegaly, moderate lymphocytosis, nodular and intrasinusoidal pattern of bone marrow infiltration, serum monoclonal band, slow benign course, and response to splenectomy. The diagnosis is made by the morphology of the circulating villous cells and their immunophenotype, which is distinct from that of chronic lymphocytic leukemia (CLL) and hairy-cell leukemia (HCL), diseases with which SLVL may be confused. When treatment is indicated, splenectomy is the treatment of choice, but some patients may require additional chemotherapy to control progression. In those circumstances, fludarabine may be the agent of choice. Despite its unique features, which, compounded, suggest that SLVL is a clinicopathologic entity, there are no specific chromosome abnormalities and problems of differential diagnosis with other B-cell NHLs, chiefly mantle-cell lymphoma (MCL), remain in a minority of patients.     

Frequency of MYD88 L256P mutation and its correlation with clinico-hematological profile in mature B-cell neoplasm

Objective/backgroundB-cell neoplasms are clonal tumors of B cells at various stages of maturation, including diffuse large B-cell lymphoma (DLBCL), chronic lymphocytic lymphoma (CLL), Burkitt lymphoma (BL), lymphoplasmacytic lymphoma (LPL)/Waldenström’s macroglobulinemia (WM), splenic marginal zone lymphoma (SMZL), nodal marginal zone lymphoma (NMZL), mantle cell lymphoma (MCL), follicular lymphoma (FL), and hairy cell leukemia (HCL). In this study, we analyzed the frequency of MYD88 L265P mutation and its correlation with clinico-hematological profile in mature B-cell neoplasms.MethodsA total of 110 consecutive cases of B-cell neoplasms showing peripheral blood and/or bone marrow infiltration were included. MYD88 L265P mutation was detected by polymerase chain reaction amplification of exon 5 of MYD88 gene, followed by restriction fragment length polymorphism analysis.ResultsAmong the 110 cases, the major group was of CLL (54.5%, n = 60), followed by HCL. Other cases included MCL, LPL, DLBCL, SMZL, NMZL, FL, and BL. MYD88 L265P mutation was seen in 21 (19.1%) cases of B-cell neoplasm, whereas 89 (80.9%) cases were negative for MYD88 L265P mutation. It was most commonly seen in LPL/WM cases followed by HCL, SMZL, CLL, and MCL cases. No case of DLBCL, FL, and BL showed MYD88 L265P mutation. Statistically significant difference was seen for hemoglobin level in CLL cases, with MYD88 L265P mutated cases showing higher mean hemoglobin levels than MYD88 wild-type cases (p = .001). For other parameters, no statistically significant difference was noted between mutated and unmutated cases.ConclusionMYD88 L265P mutation is seen in various B-cell neoplasms; it is most commonly seen in LPL/WM cases but not specific for it.     

The BH3-only mimetic ABT-737 synergizes the antineoplastic activity of proteasome inhibitors in lymphoid malignancies

Overexpression of antiapoptotic members of the Bcl-2 family is observed in approximately 80% of B-cell lymphomas, contributing to intrinsic and acquired drug resistance. Nullifying the antiapoptotic influence of these proteins can potentially overcome this resistance, and may complement conventional chemotherapy. ABT-737 is a BH3-only mimetic and potent inhibitor of the antiapoptotic Bcl-2 family members Bcl-2, Bcl-X(L), and Bcl-w. In vitro, ABT-737 exhibited concentration-dependent cytotoxicity against a broad panel of lymphoma cell lines including mantle cell lymphoma (MCL) and diffuse large B-cell lymphoma (DLBCL). ABT-737 showed synergism when combined with the proteasome inhibitors bortezomib or carfilzomib in select lymphoma cell lines and induced potent mitochondrial membrane depolarization and apoptosis when combined with either. ABT-737 plus bortezomib also induced significant apoptosis in primary samples of MCL, DLBCL, and chronic lymphocytic leukemia (CLL) but no significant cytotoxic effect was observed in peripheral blood mononuclear cells from healthy donors. In severe combined immunodeficient beige mouse models of MCL, the addition of ABT-737 to bortezomib enhanced efficacy compared with either drug alone and with the control. Collectively, these data suggest that ABT-737 alone or in combination with a proteasome inhibitor represents a novel and potentially important platform for the treatment of B-cell malignancies.