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PubMed1997

Membrane-bound proteindisulfide isomerase (PDI) is involved in regulation of surface expression of thiols and drug sensitivity of B-CLL cells.

The proteindisulfide isomerase (PDI), a multifunctional cytoplasmic enzyme with additional chaperone activity, has been shown recently, using monoclonal antibodies, to be located on the membrane of mature human B lymphocytes and B cell chronic lymphocytic leukemia (B-CLL) cells. Here, evidence is presented that this antigen exhibits catalytic activity as measured by the reductive degradation of insulin (release of A chain molecules) on intact B cells in patients suffering from B-CLL, as well as on JVM 13 cells (B-CLL cell line). More than 98% of these cells exhibited PDI activity which could be inhibited by bacitracin and also by monoclonal and polyclonal antibodies to PDI. Interestingly, surface PDI expression was strongly correlated in our study with protein-bound membrane SH groups. These surface protein thiols were specifically determined by using low concentrations of the chloromethyl-derivative based fluorescent probe 5-(and6)-(((4-chloromethyl)-benzoyl)amino)-tetramethyl-rhodamine (CMTMR) at low temperature in the presence of sodium azide in flow cytometry. The highest PDI and SH expression was found on B lymphocytes, particularly B-CLL cells. The mean fluorescence intensity (MFI) of CMTMR-positive B cells in the B-CLL line was up to 10-fold higher than that of controls, indicating a strong elevation of cell membrane-located protein thiols on malignant B cells. The link between PDI and SH expression on cell surfaces points to a functional interaction between the two. Treatment with bacitracin resulted in a strong inhibition of PDI and a dramatic increase in surface protein thiol expression of B-CLL cells. Similar effects could be observed by cell treatment with anti-PDI antibodies, indicating that this enzyme system plays a crucial role in the regulation of protein-bound SH groups. Interestingly, artificially induced protein thiol expression led to significantly higher cellular resistance to the cytostatic drugs chlorambucil, vinblastin, and cisplatin in vitro as measured by cell growth. These data suggest for the first time a regulatory effect of PDI on the surface protein thiol status of B cells. The increased expression of PDI may play a crucial role in SH-mediated protection and drug resistance in malignant B lymphocytes.

B-Lymphocytes↗

PubMed2005

Efficacy of bendamustine in patients with relapsed or refractory chronic lymphocytic leukemia: results of a phase I/II study of the German CLL Study Group.

BACKGROUND AND OBJECTIVES: Although bendamustine has been used for more than 30 years in the treatment of lymphoma, little is known about the optimal dosing schedule in relapsed or refractory B-cell chronic lymphocytic leukemia (CLL). Various dose and treatment schedules have been used empirically, and several phase II studies have shown impressive efficacy. To determine the maximal tolerated dose, dose-limiting toxicity and the optimal therapeutic dose of bendamustine for further phase III clinical trials the GCLLSG designed a phase I/II study for pre-treated CLL patients. DESIGN AND METHODS: Sixteen patients (median age 67 years) with relapsed or refractory CLL were enrolled. All patients had been pre-treated with a median of three different regimens. Bendamustine was given at a starting dose of 100 mg/m2 on day 1 and 2, repeated every 3-4 weeks. RESULTS: Major toxicities were leukocytopenia (CTC grade 3+4) in 8/16 and infections (CTC grade 3+4) in 7/16 patients. Six patients had dose-limiting toxicity which led to dose de-escalation from 100 to 70 mg/m2 in three patients. The maximum tolerated dose was 70 mg/m2. According to NCI-WG criteria, 9/16 patients (56%) responded to therapy, seven to doses <or=80 mg/m2. Two patients achieved complete remission. Five patients had a partial response and two patients stable disease. The median duration of response was 42.7 months. After a follow-up period of 53.2 months, five patients (31%) were still in remission. The median overall survival time for all patients was 45.6 months. INTERPRETATION AND CONCLUSIONS: The study confirms the excellent efficacy of bendamustine in heavily pre-treated and treatment-refractory patients, even at reduced doses of 140 mg/m2 per course. In pre-treated CLL patients, impaired bone marrow function is likely to enhance the myelotoxic side effects of bendamustine. Based on these results, the recommended optimal therapeutic dose of bendamustine in refractory CLL is 70 mg/m2 on days 1 and 2 every 4 weeks.

Aged↗

PubMed2003

Pleural effusion of a second neoplasm in a patient with B-CLL: two immunological compartments.

We report the case of a patient with a chronic lymphocytic leukemia (CLL) who later developed a metastasized large-cell neuroendocrine carcinoma of the lung that was complicated by a malignant pleural effusion. In contrast to the peripheral blood where the malignant B-CLL cells represented >99% of all lymphocytes, lymphocytes infiltrating the malignant effusion were mainly T cells. Nearly all of these T cells were CD4(+). This stood in sharp contrast to the peripheral blood where the CD4(+)/CD8(+) ratio remained balanced. A detailed analysis of the CD4(+) T cells within the malignant effusion revealed that these cells uniformly expressed a CCR7(+) CD62L(+) "non-effector" phenotype. When the monoclonal B cells within the malignant effusion were analyzed, we found that these cells, in contrast to the B-CLL cells in the peripheral blood, were negative for CD23 and expressed much higher levels of the adhesion molecules L-selectin (CD62L) and CD11a. A deficient expression of these adhesion molecules might have led to a "trapping" of the majority of B-CLL cells in the peripheral blood. This phenomenon might have contributed to the development of two highly different immunological compartments in this patient with CLL and pleural effusion of a solid tumor.

Antigens, CD↗

PubMed2004

Simultaneous manifestation of chronic lymphocytic leukemia (CLL) and hairy cell leukemia (HCL).

We report a unique case of 83-year-old Caucasian male with the initial simultaneous manifestation of chronic lymphocytic leukemia (CLL) and hairy cell leukemia (HCL). The patient presented with absolute lymphocytosis in the blood, asymptomatic generalized lymphadenopathy, and mild splenomegaly. The diagnosis of CLL was suggested from the blood film, but subsequent flow cytometric (FC) analysis on peripheral blood mononuclear cells (PBMNC) revealed two distinct abnormal clones of mature B cells. A small subpopulation (7%) of lymphoid cells expressed CD20, CD11c, FMC-7, CD103, CD25, and kappa surface light chain, consistent with HCL. The larger subpopulation (75%) of lymphoid cells expressed CD19, CD20, CD23, CD5, and lambda light chain, consistent with CLL. The expression of different immunoglobulin light chains on the circulating CLL (lambda) and HCL (kappa) cells suggested two, independent, malignant B-cell clones. Interestingly, FC analysis of bone marrow (BM) cells done 6 months later revealed bright lambda light chain expression on the HCL cells. Despite administration of several different courses of chemotherapy, the HCL subpopulation was not eliminated from the BM but remained stable between 7% and 10% of total BM lymphoid cells. The CLL, responsible for most of clinical symptoms in our patient, responded to combination chemotherapy with fludarabine and cytoxan, and later to monotherapy with rituximab.

Aged↗

PubMed2003

Production of intracellular IL-2, TNF-alpha, and IFN-gamma by T cells in B-CLL.

BACKGROUND: Recent evidence indicates that the slowly expanding population of CD5(+) B cells that characterizes B-cell chronic lymphocytic leukemia (B-CLL) could be related to defects in the response to cytokine produced by T cells that regulate apoptosis. We studied the intracellular expressions of interleukin-2 (IL-2), tumor necrosis factor-alpha (TNF-alpha), and interferon-gamma (IFN-gamma) in T-helper 1 cells (Th1 response) of B-CLL. METHODS: Peripheral blood mononuclear cells from 21 healthy individuals and purified T cells from 21 early-stage and 15 late-stage B-CLL patients were activated with phorbol myristate acetate and ionomycin. The Th1 cytoplasmic cytokines were evaluated in CD4(+) and CD8(+) T cells by flow cytometry. RESULTS: The percentages of CD4(+) and CD8(+) T cells positive for IL-2 were significantly lower in B-CLL patients than in healthy individuals (P = 0.030 and 0.049, respectively). No significant differences in TNF-alpha or IFN-gamma intracellular expressions were found between patients and healthy individuals. TNF-alpha- and IFN-gamma-expressing CD8 T cells were disease stage dependent, being significantly higher in late-stage patients (P < 0.001 for both cytokines). CONCLUSIONS: Our present observations suggested that Th1 cytokines may be of major importance in the pathogenesis of B-CLL.

Adult↗

PubMed2006

CD38 as a prognostic factor in B cell chronic lymphocytic leukaemia (B-CLL): comparison of three approaches to analyze its expression.

BACKGROUND: Increased CD38 expression by leukemic cells has been suggested as an adverse prognostic factor in B-CLL. Several approaches have been proposed to quantify its level of expression by flow cytometry. METHODS: We compared the use of (i) the percentage of CD38 positive cells, (ii) CD38 antibodies bound per cell (ABC), and (iii) a semi-quantitative method based on the shape of the CD38 histogram, within a cohort of 78 B-CLL patients. RESULTS: A decreased overall survival was seen with >30% CD38 positivity among B-CLL cells, with CD38 ABC >100, and with bimodal or unimodal, strongly positive CD38 histograms. However, patients with unimodal weakly positive CD38 histograms also showed a significantly reduced survival as did patients with intermediate proportions (i.e. 5-30%) of CD38+ cells. Furthermore, within the group with <5% CD38 positivity among their B-CLL cells, 84% of patients showed prognostically favourable mutated IGVH gene segments and 100% had low ZAP70 gene expression. For 5-30% CD38 positivity, these proportions were 50 and 83%, while for >30% CD38 positivity, these proportion were only 28 and 56%, respectively. CONCLUSIONS: We found a simple method of quantitation of CD38 expression (i.e., >5% CD38 positivity among B-CLL cells) to be sufficient to identify patients with an unfavourable prognosis. The level of CD38 expression as defined with this method correlated well with the IGVH mutation status and ZAP70 gene expression.

ADP-ribosyl Cyclase 1↗

PubMed2006

Discordant results of flow cytometric ZAP-70 expression status in B-CLL samples if different gating strategies are applied.

BACKGROUND: Recent studies have identified ZAP-70 expression status as an excellent prognostic parameter in chronic lymphocytic leukemia (CLL). ZAP-70 expression can be determined by direct antibody staining followed by flow cytometric analysis. However, there are currently several different gating strategies for analysis. We compared those strategies for ZAP-70 expression analysis. METHODS: One hundred and one patients with B-CLL were analyzed employing a directly labeled alexa-fluor-488-ZAP-70-antibody. In 27 cases, we additionally measured and analyzed ZAP-70 expression, together with healthy controls as described previously. RESULTS: Applying either T-/NK-cell isotype or healthy control analysis strategies on patient samples that were processed in parallel revealed discrepant results in 48% (12/25) of all cases. Taken together with the 74 B-CLL patients, who were analyzed with regard to average reference values, disconcordant results were obtained in 58% of the samples. We demonstrate that high variances in ZAP-70 T-/NK-cell staining within B-CLL patients, paired with a close proximity of ZAP-70 B-cell values to the suggested cut-off levels, may lead to interpretation difficulties of ZAP-70 status. CONCLUSIONS: We conclude that different gating strategies for determining flow cytometric ZAP-70 expression status produce highly discordant results. Further standardization is required before ZAP-70 can be used as a reliable prognostic parameter in immunophenotyping of B-CLL.

Adult↗

PubMed1988

Cross-linking of membrane IgM on B CLL cells: dissociation between intracellular free Ca2+ mobilization and cell proliferation.

It has been shown previously that chronic lymphocytic leukemia (CLL) B cells are frozen at different stages of activation with unique requirements for proliferation. Although most B CLL cells express surface IgM, anti-mu antibodies are able to trigger only some of them to proliferate and/or respond to B cell growth factor (BCGF) or interleukin 2 (IL2), as normal B cells. In this report we extend these observations using three different monoclonal antibodies (mAb) to human mu chain (one mitogenic in soluble form for normal B cells, the two others mitogenic only when coupled on Sepharose 4B beads). Cells from only 3 out of 11 B CLL patients proliferated in the presence of either mitogenic anti-mu. When the early events following surface Ig cross-linking, such as calcium mobilization (by flow cytometry on indo-1-labeled cells), were studied all three mAb in soluble form were able to induce a similar increase in the intracellular free calcium concentration ([Ca2+]i); analogous to [Ca2+]i rise after the mitogenic F(ab')2 anti-mu stimulation. This response was seen only in 8 out of the 12 CLL B cells studied. All B CLL cells, however, proliferate in response to a combination of phorbol ester 12,13-dibutyrate (PBt2) and ionomycin. Therefore, three patterns of response to sIg cross-linking by anti-mu could be distinguished: cells from 4 out of 12 cases proliferate and mobilize Ca2+ upon anti-mu triggering (behaving like resting B lymphocytes); in 4 other cases anti-mu lead to Ca2+ mobilization without cell proliferation; in the last 4 cases neither Ca2+ mobilization, IP3 generation (in the one case studied) nor cell proliferation are observed although these cells do proliferate directly in response to growth factors. Moreover, anti-mu stimulation in this group leads to increased proliferation in response to BCGF and IL2 suggesting an anti-Ig signaling independent of inositol phosphate metabolism. These results are interpreted in terms of differential anti-mu signaling on B cells at different stages of activation.

Antibodies, Anti-Idiotypic↗

PubMed1988

Centroblastic lymphoma of the thyroid supervening long-lasting chronic lymphocytic leukemia (B-CLL) demonstration of biclonality by immunohistochemical and gene rearrangement analysis.

A 67-year-old woman suffering since 5 years from a so far nontreated B-CLL underwent hemithyroidectomy for a rapidly enlarging tumor. Histologically, the coincidence of a centroblastic lymphoma and thyroidal infiltration by the CLL was diagnosed. Immunohistology revealed typical immunoprofils for both, B-CLL and centroblastic lymphoma on the background of B cell differentiation antigens. The bitypical immunoglobulin light chain expression--lambda on the B-CLL cells and kappa on the centroblasts--suggested biclonality. This was confirmed by gene rearrangement analysis of peripheral leukemia cells and tumor tissue. Thus, the final diagnosis of a primary thyroidal lymphoma of the centroblastic type (stage IE) arising independently from a preexisting B-CLL was achieved. Consequently, the patient received local radiotherapy. In our opinion, the designation "Richter's Syndrome", readily applied in the literature, is inappropriate for this tumor constellation.

Aged↗

PubMed2004

Discrimination of chronic lymphocytic leukemia (CLL) and CLL/PL by cytomorphology can clearly be correlated to specific genetic markers as investigated by interphase fluorescence in situ hybridization (FISH).

Although interphase fluorescence in situ hybridization (FISH) is routinely used in chronic lymphocytic leukemia (CLL), differences in the chromosomal pattern with respect to morphological subtypes of CLL (typical CLL, CLL/PL, PLL) are still under debate. We studied 153 patients with CLL and correlated cytomorphology on peripheral blood stains with FISH analysis and other prognostic markers. The percentage of prolymphocytes was calculated as a continuous variable and followed published thresholds in parallel while being correlated to FISH analysis. Higher percentages of prolymphocytes were associated significantly with deletion of 17p13. Deletion of 17p13 was most frequently observed in patients with more than 30% prolymphocytes. Trisomy 12 was found mainly in cases with 6-30% prolymphocytes. The percentage of prolymphocytes did not correlate with deletions of 11q23 or with 13q14 abnormalities. In conclusion, we suggest that further research focus on the percentage of prolymphocytes in CLL. Doing so, biologically relevant thresholds for the percentages of prolymphocytes in the peripheral blood and their association to underlying genetic markers could be investigated together with other biologically and especially prognostic markers.

Adult↗

PubMed1997

New therapeutic issues in CLL.

The treatment armamentarium for CLL has dramatically increased in the last few years. New cytotoxic agents such as the purine analogues produce a high number of responses which in some cases can be molecular. The synergism between purine analogues and other drugs (e.g., cyclophosphamide, platinum, ara-C) has opened the door to the use of purine analogues in combination chemotherapy regimens. In addition, exciting developments are being made in the field of biotherapy, particularly vaccines and monoclonal antibodies. Whereas the use of vaccines is still in its infancy, monoclonal antibodies (e.g., CAMPATH 1H) have already been proved to be highly effective in CLL treatment with response rates similar to those obtained with purine analogues. Finally, transplants of hemopoietic precursors are increasingly performed in young patients with high-risk CLL. The role of transplants in CLL, however, is still unknown and prospective, controlled studies are required to determine its potential role in the management of patients with CLL.

Humans↗

PubMed1986

Prolymphocytoid transformation of CLL: a clinical and immunological study of 22 cases.

The clinical, morphological and immunological features of 22 cases of chronic lymphocytic leukaemia in 'prolymphocytoid' transformation (CLL-Pro) are reported. Immunophenotypic patterns in CLL-Pro differ from CLL by the appearance of significant (greater than 15%) FMC7-positive components and/or increased SIg densities in most cases. Membrane TU1 and MRBC receptor expression was similar to that found in typical CLL. Morphologically, all cases showed a mixture of small lymphocytes and larger nucleolated 'prolymphocytes' although the degree of prolymphocytoid change was unrelated to immunological patterns. Clinically, the cases behaved in a very heterogeneous fashion, with some patients dying rapidly following transformation despite treatment, while others even if untreated had a long, stable and relatively benign course. It was not possible to predict which patients would do badly from immunological or morphological features but the presence of more than one involved lymph node site and the occurrence of B-symptoms appeared to identify a group that did badly. Immunological assessments were however important in therapeutic terms, drawing distinction between CLL-Pro variants and prolymphocytic leukaemia (PLL).

Humans↗

PubMed1991

Effect of TPA on fructose 2,6-bisphosphate levels and protein kinase C activity in B-chronic lymphocytic leukemia (B-CLL).

Normal B lymphocytes and peripheral mononuclear blood cells from B-chronic lymphocytic leukemia (B-CLL) patients were incubated in the presence of the tumor promoting phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA). In normal B lymphocytes and lymphocytes from five patients with B-CLL, TPA stimulation increased lymphocyte fructose 2,6-bisphosphate (fructose 2,6-P2) content and activity of 6-phosphofructo 2-kinase (PFK-2), which is the enzyme that catalyzes the synthesis of fructose 2,6-P2. This effect was evident after 6 h and maximal after 12-24 h of TPA exposure. In three patients, lymphocytes seemed to be refractory to TPA stimulation in the conditions described here. Lymphocyte stimulation by TPA was associated with the translocation of protein kinase C (PKC) from the soluble to the particulate membrane fraction, except in B-CLL lymphocytes refractory to the TPA effect. These results give further support to the existence within B-CLL of subsets of cells which are refractory to the stimulation by TPA and demonstrate that the tumor promoter TPA induces important metabolic changes in lymphocytes of some patients with B-CLL.

B-Lymphocytes↗

PubMed2005

CLL immunotoxins.

Immunotoxins composed of cell-selective ligands covalently linked to peptide toxins have been developed for the treatment of chemotherapy relapsed or refractory malignancies including chronic lymphocytic leukemia (CLL). A number of CLL immunotoxins have been clinically tested including T101-ricin A, H65-ricin A, DAB(486)IL2, DAB(389)IL2, RFB4 (dsFv)-PE38 and anti-Tac(Fv)-PE38. Remissions have occurred in some patients without significant myelosuppression, but novel agents continue to be needed. Kay and co-workers in this issue of Leukemia Research have targeted interleukin-4 receptors (IL4R) on CLL B cells with a recombinant IL4 pseudomonas exotoxin fusion protein (IL-4(38--37)-PE38KDEL). A fraction of patients (19%) had CLL cells that were extremely sensitive to the immunotoxin. This novel agent may provide an important new therapeutic for use in the treatment of CLL.

Antineoplastic Agents↗

PubMed2005

Signaling capacity of FcgammaRII isoforms in B-CLL cells.

Two main isoforms of Fcgamma receptor II (CD 32) have been described in humans: activatory FcgammaRIIA and inhibitory FcgammaRIIB. We have previously reported that B cells from a subset of chronic lymphocytic leukemia (B-CLL) patients express not only FcgammaRIIB, as normal B lymphocytes, but also the myeloid FcgammaRIIA. The aim of this study was to evaluate the signaling capacity of both FcgammaRII isoforms in B-CLL cells. We found that FcgammaRIIA expressed by leukemic cells failed to induce Ca(2+) mobilization or protein tyrosine phosphorylation, suggesting that the receptor is not functional. By contrast, FcgammaRIIB effectively diminished BCR-triggered ERK 1 phosphorylation, which indicates that it is able to transduce inhibitory signals in B-CLL cells. Moreover, we found that FcgammaRIIB homoaggregation in either B-CLL or non-malignant tonsillar B cells did not result in apoptosis as was reported for murine B splenocytes. Together, these results show that FcgammaRIIB, but not FcgammaRIIA is biologically active in B-CLL cells and might influence leukemic cell physiology in vivo.

Aged↗

PubMed2005

Establishment of a novel human B-CLL-like xenograft model in nude mouse.

We have developed a novel murine model for B-CLL by engrafting human prolymphocytic leukemia (PLL) or B-CLL cell line cells (JVM-3 and MEC-2 cell lines, respectively) into nude mice. Not only treatment of the mice was a prerequisite for the success of the graft, but also for the first time, females appeared to accept the cells more easily than males. Surprisingly, tumoral murine models for B-CLL could be established with PLL cells but not with B-CLL cells. JVM-3 cells were efficiently transplanted into nude mice through subcutaneous or intravenous routes. Irradiated female mice appeared to be the optimal recipients for tumor growth. Such murine models for human B-CLL may help the development of therapeutic agents.

Animals↗

PubMed2006

CD5 provides viability signals to B cells from a subset of B-CLL patients by a mechanism that involves PKC.

B-chronic lymphocytic leukaemia (B-CLL) is a heterogeneous disease characterized by an accumulation of B lymphocytes expressing CD5. To date, the biological significance of this molecule in B-CLL B cells remains to be elucidated. In this study, we have analysed the functional consequences of the binding of an anti-CD5 antibody on B-CLL B cells. To this purpose, we have measured the percentage of viability of B-CLL B cells in the presence or in the absence of anti-CD5 antibodies and also examined some of the biochemical events downstream the CD5-signalling. We demonstrate that anti-CD5 induces phosphorylation of protein tyrosine kinases and protein kinase C (PKC), while no activation of Akt/PKB and MAPKs is detected. This signalling cascade results in viability in a group of patients in which we observe an increase of Mcl-1 levels, whereas the levels of bcl-2, bcl-x(L) and XIAP do not change. We also report that this pathway leads to IL-10 production, an immunoregulatory cytokine that might act as an autocrine growth factor for leukaemic B cells. Inhibition of PKC prevents the induction of Mcl-1 and IL-10, suggesting that the activation of PKC plays an important role in the CD5-mediated survival signals in B cells from a subset of B-CLL patients.

Apoptosis↗

PubMed2004

Characterization of a novel B-CLL candidate gene--DLEU7--located in the 13q14 tumor suppressor locus.

Deletion of chromosome 13q14 is the most frequent genetic aberration in B-cell chronic lymphocytic leukemia (CLL), found in more than 50% of cases, indicating that this region contains a gene(s) involved in the development of CLL. However, the pathogenic gene in the critical 13q14 region has not yet been defined. Here, we have cloned and characterized a novel gene, DLEU7, located adjacent to the consensus deleted region, and overlapping the 3' end of DLEU1 tail to tail. Human DLEU7 encodes a putative 221 amino acid protein, with significant conservation in rodents. Mutational and expression analysis in primary CLL samples failed to demonstrate any specific mutations in DLEU7, but no DLEU7 expression could be detected in CLL cells. Methylation of a CpG island in the promoter region of DLEU7 was further analyzed as a possible mechanism for the absence of DLEU7 expression, and the promoter was found to be methylated in the majority of the CLL samples investigated.

Amino Acid Sequence↗