The use of cell lines for the study of Waldenström's macroglobulinemia

In this issue of Leukemia Research, Drexler and MacLeod raise questions about the origins of cell lines used in the study of Waldenström's macroglobulinemia and suggest caution in the use of these cell lines as models of this disease [Drexler HG, Macleod RAF. Malignant hematopoietic cell lines: in vitro models for the studies of Waldenström's macroglobulinemia. Leuk Res 2008].

Prothrombotic coagulation abnormalities in patients with paraprotein-producing B-cell disorders

PURPOSE

An increased incidence of thromboembolic complications has been observed in multiple myeloma (MM), especially when patients are treated with anthracycline-based chemotherapy. In patients with MM, plasma levels of several prothrombotic coagulation factors are increased, and this can contribute to the prothrombotic state of these patients. Recently, an increased thrombosis risk has also been described for other plasma cell disorders (PCDs), such as monoclonal gammopathy of uncertain significance (MGUS) and systemic amyloidosis. The aim of this study was to analyze prothrombotic coagulation disorders in patients with paraprotein-producing B-cell disorders, such as MGUS, systemic amyloidosis, Waldenström's macroglobulinemia, and MM.

PATIENTS AND METHODS

An increase in factor VIII and von Willebrand factor was observed in patients with MGUS and systemic amyloidosis that was similar to increases seen in patients with untreated MM. The highest levels were observed in patients with systemic amyloidosis.

RESULTS

We observed several coagulation abnormalities in patients with different PCDs.

CONCLUSION

These prothrombotic changes in patients with MM, systemic amyloidosis, and Waldenström's macroglobulinemia might be causally related to the observed incidence of venous thromboembolism in these forms of PCDs.

Demonstration of changes in plasma cell subsets in multiple myeloma

Increases in free light chain (FLC) production are associated with disease progression in multiple myeloma (MM). Using a double immunofluorescence staining method to produce a differential count of plasma cells in bone marrow, single populations were demonstrated, containing intact monoclonal immunoglobulins (M-Igs) in 74% and FLCs only in 8% of cases. However, 18% contained a mixture of both cell populations. Progression from cells making intact M-Ig to cells restricted to FLC only production occurred in individual cases during the course of their disease. The presence of FLC only cells was associated with shortened survival.

Establishment of BCWM.1 cell line for Waldenström's macroglobulinemia with productive in vivo engraftment in SCID-hu mice

A significant impairment in understanding the biology and advancing therapeutics for Waldenstrom's macroglobulinemia (WM) has been the lack of a representative cell line and animal model. We, therefore, report on the establishment of the BCWM.1 cell line, which was derived from the long-term culture of CD19(+) selected bone marrow lymphoplasmacytic cells isolated from an untreated patient with WM. BCWM.1 cells morphologically resemble lymphoplasmacytic cells (LPC) and propagate in RPMI-1640 medium supplemented with 10% fetal bovine serum. Phenotypic characterization by flow cytometric analysis demonstrated typical WM LPC characteristics: CD5(-), CD10(-), CD19(+), CD20(+), CD23(+), CD27(-), CD38(+), CD138(+), CD40(+), CD52(+), CD70(+), CD117(+), cIgM(+), cIgG(-), cIgA(-), ckappa(-), clambda(+), as well as the survival proteins APRIL and BLYS, and their receptors TACI, BCMA and BAFF-R. Enzyme-linked immunosorbent assay studies demonstrated secretion of IgMlambda and soluble CD27. Karyotypic and multicolor fluorescence in situ hybridization studies did not demonstrate cytogenetic abnormalities. Molecular analysis of BCWM.1 cells confirmed clonality by determination of IgH rearrangements. Inoculation of BCWM.1 cells in human bone marrow chips implanted in severe combined immunodeficient-hu mice led to rapid engraftment of tumor cells and serum detection of human IgM, lambda, and soluble CD27. These studies support the use of BCWM.1 cells as an appropriate model for the study of WM, which in conjunction with the severe combined immunodeficient-hu mouse model may be used as a convenient model for studies focused on both WM pathogenesis and development of targeted therapies for WM.

The Akt pathway regulates survival and homing in Waldenstrom macroglobulinemia

Waldenstrom macroglobulinemia (WM) is an incurable low-grade lymphoplasmacytic lymphoma. We demonstrate up-regulated Akt activity in WM, and that Akt down-regulation by Akt knockdown and the inhibitor perifosine leads to significant inhibition of proliferation and induction of apoptosis in WM cells in vitro, but not in normal donor peripheral blood and hematopoietic progenitors. Importantly, down-regulation of Akt induced cytotoxicity of WM cells in the bone marrow microenvironment (BMM) context. Perifosine induced significant reduction in WM tumor growth in vivo in a subcutaneous xenograft model through inhibition of Akt phosphorylation and downstream targets. We also demonstrated that Akt pathway down-regulation inhibited migration and adhesion in vitro and homing of WM tumor cells to the BMM in vivo. Proteomic analysis identified other signaling pathways modulated by perifosine, such as activation of ERK MAPK pathway, which induces survival of tumor cells. Interestingly, MEK inhibitor significantly enhanced perifosine-induced cytotoxicity in WM cells. Using Akt knockdown experiments and specific Akt and PI3K inhibitors, we demonstrated that ERK activation is through a direct effect, rather than feedback activation, of perifosine upstream ERK pathway. These results provide understanding of biological effects of Akt pathway in WM and provide the framework for clinical evaluation of perifosine in WM patients.

[Nodal marginal zone B-cell lymphoma: a clinicopathologic study of 10 cases]

OBJECTIVE

To study the morphologic features, immunophenotype, differential diagnosis and prognosis of nodal marginal zone B-cell lymphoma (NMZL).

METHODS

Light microscopic examination and immunohistochemical study were carried out in 10 cases of NMZL. Seven of which had follow-up information available.

RESULTS

All cases presented with good performance status at the time of diagnosis. Amongst the 7 cases with follow-up information available, most (6/7) were in advanced clinical stage (stage II to III). The one-year survival rate was 67%. A vaguely nodular growth pattern was observed in most cases of NMZL (5/10). The lymphoma was composed predominantly of atypical lymphoid cells resembling centrocytes (7/10). A predominance of monocytoid B-cell (2/10) or small lymphocytic (1/10) morphology was rare. Instead, the presence of a minor component of monocytoid B cells was not uncommon (5/10). Plasmacytoid or plasmacytic cells were also frequently found (8/10). The proliferation index ranged from 5% to 50%. Follicular dendritic cells appeared atrophic in 7 cases and variably hyperplasic in 3 cases.

CONCLUSIONS

Primary NMZL is rare. It has a unique growth pattern and most cases are composed predominantly of cells resembling centrocytes. Differential diagnosis includes lymphoplasmacytic lymphoma, lymph node involvement by extranodal marginal zone B-cell lymphoma and T-zone hyperplasia. The clinical stage is often high at presentation, with systemic dissemination. The prognosis of NMZL is thus relatively poor.

Gastric MALT Lymphoma Presenting as Waldenström's Macroglobulinemia Without Bone Marrow Involvement

We report a case of gastric mucosa-associated lymphoid tissue (MALT) lymphoma with macroglobulinemia in a 59-year-old man who presented with melena. A computed tomography scan of the abdomen showed irregular thickening of the wall of the stomach, and endoscopic examination disclosed enlarged and inflammatory folds of the fundus. Histopathologic examination of gastric samples showed mucosal infiltration by small lymphocytes, which were positive for CD20 and negative for CD10 and CD23, confirming the diagnosis of gastric MALT lymphoma. Serum electrophoresis detected a monoclonal peak and immunoelectrophoresis revealed an immunoglobulin M kappa component. Bone marrow aspirate and biopsy results were normal. The patient received chemotherapy. After treatment, he was in complete remission, and the serum monoclonal component had disappeared. Our observation is uncommon because of important macroglobulinemia occurring in gastric MALT lymphoma without bone marrow involvement.

Nonfluent aphasia in a patient with Waldenstrom’s macroglobulinemia

Waldenstrom's macroglobulinemia (WM) is an uncommon low-grade lymphoma. Cognitive impairment due to central nervous system infiltration by lymphoplasmocytoid cells (Bing-Neel syndrome) has been rarely reported. We describe a 54-year-old man who was referred to a memory disorder clinic with a 9-month history of clinically obvious nonfluent aphasia and WM. He underwent extensive neuropsychological testing, clinical examination and structural and functional brain imaging. The diagnosis of the diffuse form of the Bing-Neel syndrome was supported by abnormal lymphoid cells found in the cerebrospinal fluid. Structural and functional brain imaging revealed impairment of brain areas due to white matter changes and subsequent functional deficits mimicking the neuropsychological syndrome encountered in progressive nonfluent aphasia. The diffuse form of Bing-Neel syndrome and neurological deficits are assumed to be the result of leptomeningeal infiltration by malignant cells and/or neoplastic vascular obstruction.

Serum concentrations of angiogenic cytokines in Waldenstrom macroglobulinaemia: the ratio of angiopoietin-1 to angiopoietin-2 and angiogenin correlate with disease severity

Angiogenesis represents an essential step of disease progression in several haematological malignancies. Microvessel density is increased in 30% of patients with Waldenstrom macroglobulinaemia (WM), but there is very limited information regarding the role of angiogenic cytokines in this disease. Serum levels of vascular endothelial growth factor (VEGF), VEGF-A, angiogenin, angiopoietin (Ang)-1 and -2, and basic fibroblast growth factor (bFGF) were evaluated in 56 WM patients at different disease phases (24 untreated, 20 relapsed/refractory and 12 patients at remission) and 11 patients with immunoglobulin M type monoclonal gammopathy of undetermined significance (IgM-MGUS). All patients had increased levels of angiogenin, VEGF, VEGF-A, and bFGF compared with controls. The Ang-1/Ang-2 ratio was reduced in WM but not in IgM-MGUS patients. Angiogenin levels correlated with disease status: when compared with healthy subjects, patients with IgM-MGUS and untreated WM patients had increased angiogenin serum levels, which were higher in untreated WM patients than in MGUS. WM patients at remission had lower angiogenin serum levels compared with untreated patients, but these levels were increased again in active disease post-therapy. Angiogenin also correlated with albumin levels, while VEGF-A correlated with beta(2)-microglobulin (beta2M). Ang-1/Ang-2 ratio showed a strong, negative correlation with beta2M, and positive correlation with albumin, haemoglobin and lymphadenopathy. Our results indicate a potential use of angiogenin levels for follow-up in WM and angiogenic molecules as targets for the development of novel anti-WM agents.

Proteomic analysis of waldenstrom macroglobulinemia

To better understand the molecular changes that occur in Waldenstrom macroglobulinemia (WM), we employed antibody-based protein microarrays to compare patterns of protein expression between untreated WM and normal bone marrow controls. Protein expression was defined as a >2-fold or 1.3-fold change in at least 67% of the tumor samples. Proteins up-regulated by >2-fold included Ras family proteins, such as Rab-4 and p62DOK, and Rho family proteins, such as CDC42GAP and ROKalpha. Other proteins up-regulated by >1.3-fold included cyclin-dependent kinases, apoptosis regulators, and histone deacetylases (HDAC). We then compared the samples of patients with symptomatic and asymptomatic WM and showed similar protein expression signatures, indicating that the dysregulation of signaling pathways occurs early in the disease course. Three proteins were different by >2-fold in symptomatic versus asymptomatic, including the heat shock protein HSP90. Elevated protein expression was confirmed by immunohistochemistry and immunoblotting. Functional significance was validated by the induction of apoptosis and inhibition of proliferation using specific HDAC and HSP90 inhibitors. This study, therefore, identifies, for the first time, multiple novel proteins that are dysregulated in WM, which both enhance our understanding of disease pathogenesis and represent targets of novel therapeutics.

[Malignant transformation of monoclonal gammopathy of undetermined significance]

Monoclonal gammopathy of undetermined significance (MGUS) is found in approximately 3% of the general population aged 50 years or older. MGUS is a premalignant state. The risk of malignant transformation is about 1% per year. Some factors predictive of malignant transformation have been identified: type of serum monoclonal protein, monoclonal protein value, bone marrow plasmocytosis and serum free light chain ratio. Predictive scores combining these factors have recently been proposed and make it possible to identify groups of patients with significantly different rates of transformation. These scores require validation. These scores will probably allow individualization of management and monitoring.

Bilateral orbital tumor formation and isolated facial palsy in Waldenstrom’s macroglobulinemia

A 32-year-old lady presented with bilateral painful proptosis and left infranuclear facial palsy. She was mildly anemic. Ocular examination revealed a firm non-tender mass in the super lateral quadrant of both orbits. Fine-needle aspiration cytology from the orbital mass showed the presence of lymphoplasmacytoid cells. Bone marrow aspiration also showed the presence of similar cells. An IgM monoclonal gammopathy was seen on serum protein electrophoresis. A diagnosis of Waldenstrom's macroglobulinemia was made on the basis of these findings. Hyperviscosity retinopathy is the most commonly reported ocular abnormality in Waldenstrom's macroglobulinemia. Orbital tumor formation and cranial nerve palsies are rarely reported in this condition. We describe the first case of Waldenstrom's macroglobulinemia presenting as an isolated orbital mass and facial nerve palsy.

Gene expression profiling of B lymphocytes and plasma cells from Waldenström's macroglobulinemia: comparison with expression patterns of the same cell counterparts from chronic lymphocytic leukemia, multiple myeloma and normal individuals

The tumoral clone of Waldenström's macroglobulinemia (WM) shows a wide morphological heterogeneity, which ranges from B lymphocytes (BL) to plasma cells (PC). By means of genome-wide expression profiling we have been able to identify genes exclusively deregulated in BL and PC from WM, but with a similar expression pattern in their corresponding cell counterparts from chronic lymphocytic leukemia (CLL) and multiple myeloma (MM), as well as normal individuals. The differentially expressed genes have important functions in B-cell differentiation and oncogenesis. Thus, two of the genes downregulated in WM-BL were IL4R, which plays a relevant role in CLL B-cell survival, and BACH2, which participates in the development of class-switched PC. Interestingly, one of the upregulated genes in WM-BL was IL6. A set of four genes was able to discriminate clonal BL from WM and CLL: LEF1 (WNT/beta-catenin pathway), MARCKS, ATXN1 and FMOD. We also found deregulation of genes involved in plasma cell differentiation such as PAX5, which was overexpressed in WM-PC, and IRF4 and BLIMP1, which were underexpressed. In addition, three of the target genes activated by PAX5 - CD79, BLNK and SYK - were upregulated in WM-PC. In summary, these results indicate that both PC and BL from WM are genetically different from the MM and CLL cell counterpart.

Waldenstrom's macroglobulinemia presenting with spinal cord compression: a case report

Waldenstrom's macroglobulinemia (WM) is a rare lymphoplasmacytic lymphoma characterized by a wide range of clinical presentations related to direct tumor infiltration and the production of IgM. Most commonly it presents with cytopenia, hepatosplenomegaly, lymphadenopathy, constitutional symptoms, and hyperviscosity syndrome. We report a case of WM in an 81-year-old man who initially presented with severe back pain. The patient had no peripheral lymphadenopathy or hepatosplenomegaly and his peripheral blood smear was normal. MRI of the spine revealed an epidural mass causing spinal cord compression at T9. Surgical decompression was performed and pathological analysis of the mass revealed a lymphoproliferative B-cell process. The diagnosis of WM was established after cytomorphologic and immunohistochemical analysis of the patient's bone marrow revealed the presence of a lymphoid/lymphoplasmacytoid-like bone marrow infiltrate along with an elevated serum IgM level. The patient responded both clinically and serologically to local radiotherapy. This case is unusual because the patient lacked all common clinical features of WM. This is the first reported case of epidural spinal cord compression as the initial manifestation of WM, adding to the spectrum of clinical presentations seen in this disease.

Cutaneous infiltration with Waldenström macroglobulinemia

A 59-year-old Japanese man was diagnosed as Waldenström macroglobulinema. With impaired general performance and a 2-year history of pruritic eruptions that were initially confined to the forearms, but later involved the face, limbs, and trunk. A skin biopsy that was performed on the forehead showed infiltration with abnormal cells of the dermis around the central vessels. PCR analysis of the skin biopsy showed immunoglobulin heavy chain rearrangement. As the rearrangement band occurred at the same site as that of the bone marrow aspiration, skin infiltration with abnormal cells was proven.

Pulmonary lymphoma of mucosa-associated lymphoid tissue type followed as a long-standing indeterminate lesion in immunoglobulin M-type paraproteinemia

An 82-year-old woman with monoclonal immunoglobulin (Ig) M-type paraproteinemia had a large opacity in the right lung field. The abnormal shadow on roentgenogram had persisted for more than 6 years since the initial diagnosis of paraproteinemia, which had been diagnosed as Waldenström's macroglobulinemia (WM). Computed tomography revealed the lesion as a pulmonary tumor which was finally diagnosed as a marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) after surgical removal. MALT lymphoma constitutes the majority of primary pulmonary lymphomas and is often associated with monoclonal IgM-type paraproteinemia as well as WM, a distinctive lymphoproliferative disorder. Pulmonary MALT lymphoma should frequently be suspected in case of an indeterminate pulmonary tumor with IgM-type paraproteinemia.

Mast cells in Waldenstrom's macroglobulinemia support lymphoplasmacytic cell growth through CD154/CD40 signaling

Bone marrow (BM) mast cells (MC) are commonly found in association with lymphoplasmacytic cells (LPC) in patients with Waldenström's macroglobulinemia (WM). We therefore sought to clarify the role of MC in WM. Co-culture of sublethally irradiated HMC-1 MC, KU812 basophilic cells, or autologous BM MC along with BM LPC from WM patients resulted in MC dose-dependent tumor colony formation and/or proliferation as assessed by 3H-thymidine uptake studies. Furthermore, by immunohistochemistry, multicolor flow cytometry and/or RT-PCR analysis, CD40 ligand (CD154), a potent inducer of B-cell expansion, was expressed on BM MC from 32 of 34 (94%), 11 of 13 (85%), and 7 of 9 (78%) patients, respectively. In contrast, MC from five healthy donors did not express CD154. By multicolor flow cytometry, CD154 was expressed on BM LPC from 35 of 38 (92%) patients and functionality was confirmed by CD154 and CD40 agonistic antibody stimulation, which induced proliferation, support survival and/or pERK phosphorylation of LPC. Moreover, MC induced expansion of LPC from 3 of 5 patients was blocked in a dose dependent manner by use of a CD154 blocking protein. These studies demonstrate that in WM, MC may support tumor cell expansion through constitutive CD154-CD40 signaling and therefore provide the framework for therapeutic targeting of MC and MC-WM cell interactions in WM.

Nuclear BCL-10 expression is common in lymphoplasmacytic lymphoma/Waldenström macroglobulinemia and does not correlate with p65 NF-kappaB activation

B-cell lymphoma 10 (BCL-10) is expressed in the cytoplasm of normal germinal center and marginal zone B-cells and is involved in lymphocyte development and activation. Aberrant nuclear expression of BCL-10 occurs in a subset of extranodal marginal zone B-cell lymphomas (MALT lymphomas), primarily those with the t(1;14)(p22;q32) or t(11;18)(q21;q21). Little is known about BCL-10 expression in lymphoplasmacytic lymphoma/Waldenström macroglobulinemia (LPL/WM). We assessed for BCL-10 in 51 bone marrow (BM) specimens involved by LPL/WM using immunohistochemical methods. All patients had monoclonal IgM in serum. Extent of BM involvement was assessed using PAX-5/BSAP and CD20 immunostains and the pattern and percentage of B-cells positive for BCL-10 was determined. The p65 subunit of nuclear factor-kappa B (NF-kappaB), a molecule downstream of BCL-10, was also assessed immunohistochemically. Nuclear BCL-10 staining was present in 28/51 (55%) specimens. BCL-10 expression correlated with greater extent of BM involvement (P=0.001), but did not correlate with serum IgM paraprotein levels, type of immunoglobulin light chain, or clinical variables. Nuclear expression of the p65 subunit of NF-kappaB was detected in 17/50 (34%) specimens, suggesting that NF-kappaB is active in a subset of LPL/WM. p65 NF-kappaB activation did not correlate with nuclear BCL-10 immunostaining. Cytogenetic analysis in 29 cases showed no evidence of the t(1;14) or t(11;18). These results indicate that nuclear BCL-10 expression is common in LPL/WM and does not correlate with MALT lymphoma-associated translocations or p65 NF-kappaB nuclear staining.

Unusual evolution of Waldenstrom's macroglobulinemia into osteolytic myeloma

We report the unusual transformation of a case of Waldenström's macroglobulinemia (WM) into IgM multiple myeloma (MM). The initial clinical and biological presentation of the disease was typical smouldering WM, with lymphocytic infiltration of the bone marrow. Five years later, signs of transformation appeared: the patient presented with diffuse osteolytic bone lesions without organomegaly, and the bone marrow was infiltrated with characteristic malignant plasma cells. Electron microscopy (EM) examination showed that the endoplasmic reticulum (ER) of the dysmorphic plasma cells contained monoclonal IgM. Immunolabeling for calreticulin, a resident protein of the ER, demonstrated unequivocally that the characteristic intranuclear inclusions were indeed part of ER. Flow cytometry revealed an MM profile for the cellular proliferation. Molecular biology performed on the final marrow could only retrieve a single cellular clone. In conclusion, this is the first documented description of the transformation of typical WM into an aggressive form of MM.

“Primary” antiphospholipid syndrome evolving into Waldenstrom’s macroglobulinaemia: a case report

A 57-year-old woman with a history of transient ischaemic attacks and six recurrent foetal losses accompanied by elevations of antiphospholipid antibodies was diagnosed as having a "primary" antiphospholipid syndrome. She was followed up for 5 years, and she developed anaemia, leucopenia and splenomegaly. A bone marrow trephine was diagnostic of Waldenstrom's macroglobulinaemia. A false positive serological test for syphilis was demonstrated and apparently had been noted in her second pregnancy more than 20 years prior to her presentation with an antiphospholipid syndrome. There had previously been no indication to perform serum electrophoretic studies. This case illustrates the importance of this investigation in any middle-aged patient presenting with an antiphospholipid syndrome and a monoclonal gammopathy This finding might presage the development of a more serious condition, even years later (as in our patient).