Interleukin 4 strongly augments or inhibits DNA synthesis and differentiation of B-type chronic lymphocytic leukemia cells depending on the co-stimulatory activation and progression signals

Functional pharmacogenomics and toxicity of PolyPurine Reverse Hoogsteen hairpins directed against survivin in human cells

PolyPurine Reverse Hoogsteen (PPRH) hairpins constitute a relatively new pharmacological agent for gene silencing that has been applied for a growing number of gene targets. Previously we reported that specific PPRHs against the antiapoptotic gene survivin were able to decrease viability of PC3 prostate cancer cells by increasing apoptosis, while not acting on HUVEC non-tumoral cells. These PPRHs were efficient both in vitro and in vivo. In the present work, we performed a functional pharmacogenomics study on the effects of specific and unspecific hairpins against survivin. Incubation of PC3 cells with the specific HpsPr-C-WT led to 244 differentially expressed genes when applying the p < 0.05, FC > 2, Benjamini-Hochberg filtering. Importantly, the unspecific or control Hp-WC did not originate differentially expressed genes using the same settings. Gene Set Enrichment Analysis (GSEA) revealed that the differentially expressed genes clustered very significantly within the gene sets of Regulation of cell proliferation, Cellular response to stress, Apoptosis and Prostate cancer. Network analyses using STRING identified important interacting gene-nodes within the response of PC3 cells to treatment with the PPRH against survivin, mainly POLR2G, PAK1IP1, SMC3, SF3A1, PPARGC1A, NCOA6, UGT2B7, ALG5, VAMP7 and HIST1H2BE, the former six present in the Gene Sets detected in the GSEA. Additionally, HepG2 and 786-O cell lines were used to carry out in vitro experiments of hepatotoxicity and nephrotoxicity, respectively. The unspecific hairpin did not cause toxicity in cell survival assays (MTT) and produced minor changes in gene expression for selected genes in RT-qPCR arrays specifically developed for hepatic and renal toxicity screening.

Modeling the chronic lymphocytic leukemia microenvironment in vitro

Microenvironments within the lymph node and bone marrow promote proliferation and drug resistance in chronic lymphocytic leukemia (CLL). Successful treatment of CLL must therefore target the leukemic cells within these compartments. A better understanding of the interaction between CLL cells and the tumor microenvironment has led to the development of in vitro models that mimic the mechanisms that support leukemic cell survival and proliferation in vivo. Employing these models as part of the pre-clinical evaluation of novel therapeutic agents enables a better approximation of their potential clinical efficacy. In this review we summarize the current literature describing how different aspects of the tumor microenvironment have been modeled in vitro and detail how these models have been employed to study the biology of the disease and potential efficacy of novel therapeutic agents.

Novel use of the fluorescent dye 5-(and-6)-chloromethyl SNARF-1 acetate for the measurement of intracellular glutathione in leukemic cells and primary lymphocytes

Glutathione (GSH) plays an important role in protecting cells against injury, particularly during oxidative stress. Alterations in GSH metabolism are becoming the focus of attention in many diseases such as cancer, neurodegeneration, and AIDS. As such, a rapid assessment of GSH levels in a clinical setting is of increasing importance. We tested the efficacy of the thiol-labeling fluorescent dye CM-SNARF in its ability to measure variations in GSH concentration using a visible-light flow cytometer. GSH levels in I83, Jurkat, and primary lymphocytes were depleted with buthionine sulfoximine (BSO) or diamide, or increased with N-acetylcysteine (NAC). Following each treatment, cells were divided and either labeled with CM-SNARF followed by flow cytometry analysis, or assayed for GSH using a biochemical method. BSO treatment caused a maximal 87-90% decrease in GSH and 68-76% decrease in fluorescence units. Diamide depleted GSH 91-95%, corresponding to a fluorescence decrease of 85-88%. NAC treatment increased GSH levels 27% and fluorescence 12-19%. The overall correlation (R2) between mean GSH concentration and mean fluorescence was 0.80-0.88. CM-SNARF can be used to semi-quantitatively and rapidly determine intracellular variations in GSH concentration in the range of 10-150 nmoles GSH/mg protein.

Imatinib sensitizes CLL lymphocytes to chlorambucil

The effect of imatinib on chlorambucil (CLB) cytotoxicity in chronic lymphocytic leukemia (CLL) lymphocytes was examined in vitro. Imatinib sensitizes the WSU and I83 human CLL cell lines, 10- and two-fold, respectively, to CLB. Furthermore, in primary cultures of malignant B-lymphocytes obtained from 12 patients with CLL (seven patients were untreated and five treated with CLB), imatinib synergistically sensitized these lymphocytes from two- to 20-fold to CLB. This synergistic effect was observed at concentrations of imatinib (</=10 microM), which are achievable in patients with minimal toxicity. Moreover, the combination of both drugs results in increased apoptosis in CLL cell lines. These results suggest that imatinib should be useful in improving the therapeutic index of CLB in CLL. The mechanism of action appears to involve imatinib inhibition of c-abl kinase activity with an associated decrease in CLB-induced Rad51 phosphorylation and CLB-induced Rad51 nuclear foci, suggesting that imatinib decreases Rad51-related DNA repair of CLB-induced DNA lesions. Altogether, our results suggest that imatinib is a promising adjuvant therapy to CLB treatment of CLL.

Thioredoxin prolongs survival of B-type chronic lymphocytic leukemia cells

Thioredoxin (Trx) is a ubiquitous protein disulfide oxidoreductase with antioxidant, cytokine, and chemotactic properties. Previously, we showed that Trx, in synergy with interleukin 1 (IL-1), IL-2, IL-4, tumor necrosis factor  (TNF-), and CD40-ligation induced S-phase entry and mitosis in normal B cells and B-type chronic lymphocytic leukemia (B-CLL) cells. The viability of B-CLL cells stimulated by these protocols is high, and it has been hypothesized that the overexpression of Bcl-2 found in B-CLL protects the cells from apoptosis in vitro and in vivo. In this study, we have analyzed the response of cells derived from 12 samples of patients with B-CLL to recombinant human Trx in spontaneous apoptosis, with special reference to the Bcl-2 expression. Long-term cultures of B-CLL clones showed significantly higher viability when supplemented with human Trx (P = .031), also exemplified with clones surviving more than 2 months. Short-term cultures of B-CLL cells exposed to 1 μg/mL of Trx for 1, 5, or 12 days maintained expression or delayed down-regulation of Bcl-2 compared with control cultures containing RPMI 1640 medium and 10% fetal calf serum only (P = .032, .002, .026, respectively). All B-CLL cells expressed constitutive Trx at varying but low levels, in contrast to adult T-cell leukemias, which overexpress Trx, as previously reported. We found that Trx added to B-CLL cells increased in a dose-dependent fashion the release of TNF-, which has been suggested to be an autocrine growth factor for these cells. In conclusion, we have found that human recombinant Trx induced TNF- secretion, maintained Bcl-2, and reduced apoptosis in B-CLL cells.

Staphylococcus aureus Cowan strain 1 activation of B-chronic lymphocytic leukaemia cells augments the response to CD40 stimulation

The signals involved in regulating the proliferation, differentiation and survival of B-chronic lymphocytic leukemia (B-CLL) cells are fully understood. B-CLL cells have been found to respond poorly to various activation signals and only after successful Epstein-Barr virus (EBV) transformation has it been possible to maintain such cells in long-term cultures. In this work we describe a new method to activate and induce proliferation in B-CLL cells and to maintain such cells in long-term culture for longer than 1 month. We used a combination of protocols in an attempt to mimic some of the signals of a thymus-dependent immune response. The B-CLL cells were first activated with Staphylococcus aureus Cowan strain 1 (SAC) particles plus thioredoxin (Trx), followed by stimulation with interleukin (IL)-2 + Trx. This treatment primed the cells for further stimulation with anti-CD40 monoclonal antibody (MoAb) presented on irradiated CD32L cells (the CD40-system) or soluble CD40 Ligand, and a combination of Trx and cytokines (IL-4 + IL-10), which allowed the cells to be maintained for up to 1 month with preserved viability and a variable rate of proliferation. However, induced proliferation of the B-CLL cells was limited to approximately 1 month, suggesting that additional signals are required to facilitate further proliferation.

Interleukin-10 inhibits the in vitro proliferation of human activated leukemic CD5+ B-cells

B-cell chronic lymphocytic leukemia (B-CLL) is characterised by the proliferation and accumulation of sIgM+/CD5+ B-cells that fail to progress to the final stages of B-cell development. Despite their developmental arrest, leukemic CD5+ B-cells can undergo proliferation in vitro in the presence of different activators including phorbol esters, antibodies to cell surface antigens and human cytokines. Interleukin-10 (IL-10) has recently been found to inhibit CLL B-cell function in vitro by inducing apoptosis and down-regulating expression of bcl-2. Here, we examined the effect of IL-10 on proliferation, RNA synthesis, immunoglobulin (IgM) secretion and viability of leukemic CD5+ B-cells induced by activation with the phorbol ester PMA, alone or in combination with anti-Ig. IL-10 reduced PMA and PMA/anti-Ig induced proliferation and RNA synthesis by 50-80% and 15-40% respectively. Although proliferation and RNA synthesis induced by PMA/anti-Ig could be enhanced by the addition of IL-2, IL-4, IL-13, IFN-gamma or TNF-alpha, the presence of these cytokines failed to abrogate the IL-10-mediated inhibition of leukemic CD5+ B-cell activation. In contrast to the effects on proliferation and RNA synthesis, IL-10 did not inhibit IgM secretion, and had only a minimal effect on the viability of activated cells. Our results indicate that IL-10 inhibits proliferation of leukemic CD5+ B-cells by a mechanism distinct from induction of apoptosis and support the proposal for the utilisation of IL-10 in the therapy of B-CLL.

T-cell derived cytokines co-stimulate proliferation of CD40-activated germinal centre as well as follicular lymphoma cells

Follicular lymphomas, the malignant counterparts of normal germinal centre (GC) B-cells, grow in vivo in close association with polyclonal T-cells, predominantly from the T-helper cell type. T-cell-derived growth factors are involved in the development of GC B-cells. However, their role in the pathogenesis of follicular lymphomas has not been clearly defined. We investigated the co-stimulatory activity of 14 cytokines (interleukin-1 to -8, IL-10, IL-13, INF-alpha, TNF-alpha, GM-CSF and SCF) on the proliferation of CD40-activated follicular lymphoma cells in comparison to tonsillar GC B-cells. Tonsillar GC B-cells (n = 4), malignant cells from diagnostic lymph node biopsies of patients with follicular (n = 4) or transformed (n = 4) lymphomas were grown on irradiated CD40-ligand transfectants, with and without cytokines. [3H]-thymidine uptake was measured at day 7. IL-10 and IL-4 proved to be the most potent co-stimulators of proliferation of tonsillar GC B-cells, whereas proliferation of follicular lymphoma cells was co-stimulated by IL-4. The fact that IL-4 is a T-cell derived cytokine, suggests that lymphoma infiltrating T-cells play a role in the growth of these malignancies. Moreover, proliferation of both non-neoplastic tonsillar GC B-cells and follicular lymphomas is co-stimulated by T-cell derived cytokines, indicating that responsiveness to paracrine factors may not be a characteristic of the malignant phenotype.

Chronic Lymphocytic Leukemia B Cells Are Resistant to the Apoptotic Effects of Transforming Growth Factor-β

Chronic lymphocytic leukemia (CLL) is the most common leukemia of the western world and is characterized by a slowly progressing accumulation of clonal CD5+ B cells. Our laboratory has investigated the role of transforming growth factor-β (TGF-β) and interleukin-4 (IL-4) in the pathogenesis of B-cell expansion in CLL. In vitro addition of TGF-β did not increase spontaneous apoptosis of B cells from most CLL patients, as determined using the TUNEL method, compared with a twofold increase observed in cultures of normal B cells. There was similar expression of TGF-β type II receptors on both CLL B cells and normal B cells. In contrast to apoptosis, CLL B-cell proliferation was variably inhibited with addition of TGF-β. In vitro addition of IL-4, previously reported to promote CLL B-cell survival, dramatically reduced spontaneous apoptosis of CLL B cells compared with normal B cells. CLL B-cell expression of IL-4 receptors was increased compared to normal B cells. Thus, our results show aberrant apoptotic responses of CLL B cells to TGF-β and IL-4, perhaps contributing to the relative expansion of the neoplastic clone.

Cellular interactions among marrow stromal and normal/neoplastic pre-B- and B-lymphoblastic cells

The direct interaction between B-cells, both normal and neoplastic, and marrow stromal cells (MSC) or MSC-secreted extracellular matrix proteins is believed to play a decisive role in lymphopoiesis as well as in the sustained proliferation and homing of lymphoid malignancies. Although information has been accruing on possible obligatory cell-cell and cell-extracellular matrix adhesion molecules, our current state of knowledge regarding B-cell interaction with the marrow microenvironment is rather limited. We discuss in this review what is currently known regarding adhesion molecules involved in the apposition between B-cells and MSC. In addition, we describe how the cellular interactions are modulated by cytokines present in the marrow microenvironment. Further, we present possible signal transduction pathways activated by B-cell/MSC apposition and attempt to integrate in vitro data with in vivo observations. We close this review by providing implications for novel clinical and therapeutic applications based on the current knowledge of B-cell/MSC adhesion mechanisms and signaling pathways.

New perspectives on the approach to chronic lymphocytic leukemia

Investigation of the biological actions of loxoribine in chronic lymphocytic leukemia (CLL) was undertaken because of the pervasive immunostimulatory effects of the nucleoside on normal B cells. In vitro studies with cells from a spectrum of CLL patients demonstrate that loxoribine induces B-CLL cells to enter and traverse the cell cycle. This is reflected by marked increases in DNA synthesis, by standard morphological criteria, and by flow cytometric evaluation of cell cycle status and of cell surface activation markers. Cells from about 75% of patients studied evince this response. Analysis of a variety of biological parameters indicate that only the ratio of T cells (CD4+ or CD8+) to B-CLL cells correlates with induction and degree of proliferative response. Co-stimulation with loxoribine and IL-2 results in modest proliferative synergy, presumably due to upregulation of IL-2R alpha expression on B-CLL cells by loxoribine. Prolonged exposure of B-CLL cells to stimulatory concentrations of loxoribine frequently culminates in progression of the responsive cells to apoptosis. The capacity of loxoribine to transiently approximate the reversible transformation of a low grade B cell malignancy to one of a higher grade presents the opportunity for evaluation of cycle-active drugs under these conditions. Recent studies indicate that pre-treatment of B-CLL cells with loxoribine results in synergistic killing of leukemic cells with cycle-active drugs. The ability to induce B-CLL cells into cell cycle entry and/or into either activation-induced apoptosis or into phases of the cell cycle sensitive to cytotoxic therapy opens up new perspectives for the development of potentially curative strategies for this chronic leukemia.

Expression and production of cytokines by heterohybrids and their parental B cells in CLL

Three hybrids derived from CD5+ B cell chronic lymphocytic leukemia (B-CLL) and their parental B cells were studied for phenotypic evolution, immunoglobulin (Ig), tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) secretion. When phenotypic evolution was examined, hybrids showed the loss of classical B cell markers, indicating that they follow the same pattern of phenotypic differentiation as normal B cells. Hybrids displayed spontaneous high Ig secretion, which did not appear to be modified through stimulation by phorbol 12-myristate 13-acetate (PMA), recombinant interferon-gamma (rIFN-gamma) and Staphylococcus aureus Cowan I (SAC). Parental cells secreted minimal amounts of Ig spontaneously or through IFN-gamma and SAC stimulation, whereas PMA succeeded in increasing this secretion. An opposite pattern was observed when TNF-alpha and IL-6 secretion an expression at the mRNA level were assessed in hybrids and parental cells. TNF-alpha and IL-6 were spontaneously secreted by parental cells and this secretion was increased after PMA and SAC stimulation, both cytokine secretion and expression at the mRNA level were negative in hybrid cells. The absence of expression of these cytokines could be explained either by chromosomal loss or by down regulation. These results indicate that when parental CLL cells are induced to differentiate in the heterohybrid model, they acquire high spontaneous secretion of Ig, lose the classical B cell phenotypic markers and down regulate the expression of the cytokines studied.

Nucleoside transporters, bcl-2 and apoptosis in CLL cells exposed to nucleoside analogues in vitro

The purine nucleoside analogues fludarabine (F1) and chlorodeoxyadenosine (2-CdA) are considered to be cell cycle specific agents which require DNA synthesis for cytotoxicity. However, their efficacy in the treatment of CLL, an indolent lymphoid malignancy suggests additional mechanisms of action. Like cytosine arabinoside (AraC), F1 and 2-CdA gain access to the cell via a specific nucleoside transporter (NST) protein. To investigate the mode of action of these drugs in CLL, we used a fluorescent ligand for the NST (5'-(SAENTA- x8)-fluorescein) and 3-colour flow cytometry to determine NST expression on CD5+/CD19+ B-cells from the peripheral blood (PB) of patients with CLL. NST levels on these cells was found to be not significantly different from normal control lymphocytes (mean = 485 +/- 425) vs. (mean = 553 +/- 178). Exposure to varying concentrations (0, 3 microM and 30 microM) of F1 and 2-CdA, however, resulted in an upregulation of NST (mean = 1552 +/- 775 with 30 microM FL; mean = 3392 +/- 2197 with 30 microM 2-CdA) after 48. "Large" lymphoid cells (not present in normal PB) were found to express significantly more NST (mean = 2540 +/- 2861) and have a higher proliferative capacity than "small" cells (mean = 357 +/- 517 NST/cell). Incubation of CLL cells with F1 (n = 6) and 2-CdA (n = 8) in vitro over 48 h also resulted in an increase in the proportion of cells in S-phase (0 microM = 0.2 + 2 - 0.1; 30 microM FL = 2.4 +/- 2.0; 30 microM 2-CdA = 3.3 +/- 1.3) and a significant increase in morphologically identifiable apoptosis. Apoptosis was confirmed by flow cytometric DNA analysis (0 microM = 13 +/- 8%; 30 microM FL = 40 +/- 20%; 30 microM 2-CdA = 48 +/- 11%). In situ hybridization using a biotinylated cDNA bcl-2 probe demonstrated that bcl-2 mRNA expression was markedly decreased in treated cells after 24 h. These studies have demonstrated that: (1) NST expression on CLL lymphocytes is low; (2) in vitro exposure to the analogues increases both the level of NST expression and the % cells in S-phase; (3) exposure to the analogues downregulates bcl-2 expression and increases apoptosis.

Clinical heterogeneity reflects biologic diversity in chronic lymphocytic leukemia

As the incidence of B cell chronic lymphocytic leukemia increases in an aging population, it becomes more important to re-evaluate our understanding of the disease process and current therapy. Previous treatment strategies have been, for the most part, unsuccessful in prolonging survival and thus new approaches are needed. More intense cellular and molecular research on the biologic diversity of this neoplasm will further our understanding of the causes of clinical heterogeneity and refine our ability to predict progression. New approaches, based on alterations of neoplastic cell growth by cytokines or chemotherapeutic agents, may enable clinicians to 'customize' individual treatments based on the stages of CLL B cell differentiation and our understanding of factors involved in the regulation of apoptosis and proliferation at those stages. Taken together, these efforts should ultimately yield much new information that will lead to reduced morbidity and mortality in B-CLL, the most common form of human leukemia.

Receptor for interleukin 13. Interaction with interleukin 4 by a mechanism that does not involve the common gamma chain shared by receptors for interleukins 2, 4, 7, 9, and 15

Interleukin 13 (IL-13) shares many biological properties with IL-4, and although the receptor for IL-4 (IL-4R) has been characterized, the expression and structure of IL-13 receptor are unknown. We report here that human renal cell carcinoma (RCC) cells express large numbers of functional IL-13R. Human B lymphocytes and monocytes expressed a very small number of IL-13R, while resting or activated human T cells expressed little or no IL-13R. IL-4 did not compete for IL-13 binding, while IL-13 competed for IL-4 binding, even though IL-4R and IL-13R are structurally distinct on human RCC cells. IL-13 cross-linked with one major protein that is similar in size to the gamma c subunit of IL-2, -4, -7, -9, and -15 receptors but was not recognized by anti-gamma c or anti-IL-4R antibodies. IL-4, on the other hand, cross-linked with two major proteins, the smaller of which appears to be similar in size to IL-13R and gamma c, but (like the IL-13R) it did not react with anti-gamma c antibody. Although as shown in this study and in previous studies, gamma c is a functional component of IL-4R in lymphoid cells, it does not appear to be associated with IL-4R on RCC cells. Even in the absence of common gamma chain IL-4 and IL-13 were able to up-regulate intracellular adhesion molecule-1 antigen on RCC cells. These data suggest that the interaction of IL-13 with IL-4R does not involve gamma c and IL-13R itself may be a novel subunit of the IL-4R.

Phorbol ester activates CD5+ leukaemic B cells via a T cell-independent mechanism

B cell chronic lymphocytic leukaemia (B-CLL) is characterized by the proliferation and accumulation of sIgM+ CD5+ lymphocytes that fail to progress to the final stages of B cell development. Stimulation of unfractionated PBL from three patients with B-CLL with the phorbol ester PMA and the mitogens PHA and PWM resulted in significant increases in cell proliferation, RNA synthesis and IgM secretion when compared to unstimulated cell populations. PMA was the most potent inducer of IgM secretion and this occurred irrespective of the presence of residual T cells. PMA-induced proliferation and RNA synthesis was also independent of T cells. However, in the presence of T cells, these parameters of cellular activation were enhanced during in vitro culture. Thus, the inductive ability of PMA on CD5+ CLL B cells was independent of T cells. In contrast, activation and differentiation of the malignant CD5+ B cells into IgM-secreting cells following culture with mitogens did not occur in the absence of T cells.

Stoichiometry of the complex of human interleukin-4 with its receptor

A large number of cytokines have been shown to possess a four-helix bundle structure with a unique up-up-down-down connectivity. The receptors for this family of cytokines have been shown to be homologous as well, each possessing two tandem repeats of a fibronectin type III-like domain. The crystal structure of human growth hormone bound to the soluble portion of its receptor has served as the only experimentally-determined example of the interaction between the four-helix bundle cytokines and their receptors: two identical receptor subunits bind to different epitopes on the same growth hormone ligand. We have conducted a series of experiments to determine if this structural paradigm is true for interleukin-4 and interleukin-4 receptor. Native polyacrylamide gel electrophoresis and gel filtration chromatography reveal that interleukin-4 forms a tight 1:1 complex with the system.

The molecular basis of X-linked severe combined immunodeficiency: the role of the interleukin-2 receptor gamma chain as a common gamma chain, gamma c

X-linked severe combined immunodeficiency is characterized by severe and persistent infections from early life resulting from profound impairment of both cellular and humoral immune function. XSCID is characterized by an absence or diminished number of T cells and histologic evidence of hypoplastic and abnormal differention of the thymic epithelium. The discovery that this disease results from the mutations of the IL-2R gamma chain was surprising since IL-2-deficient mice and human SCID patients had milder phenotypes. This led to the speculation that IL-2R gamma would prove to be a common gamma chain, gamma c, which would play important roles in other cytokine receptors in addition to the IL-2 receptor. There is now compelling evidence to support a role in at least two other cytokine receptors, namely the IL-4 and IL-7 receptors. Thus, with inactivation of gamma c, multiple cytokine systems are simultaneously affected, resulting in the profoundly impaired phenotype of XSCID. It is possible and even likely that gamma c will be found to be a functional component of additional receptors as well. These findings have resulted in a significant improvement in our understanding of the pathophysiologic development of the defects in XSCID and also have important ramifications for prenatal and postnatal diagnosis, carrier female identification, and gene therapy for XSCID.

Interleukin-4 (IL-4) inhibits proliferation and spontaneous cytokine release by chronic lymphocytic leukaemia cells

Previous studies have shown that interleukin-4 (IL-4) may have both stimulatory and inhibitory effects on the growth of normal and malignant B-cells in vitro. We studied the effects of IL-4 on tumour necrosis factor (TNF) induced and spontaneous proliferation (3H-TdR incorporation) and spontaneous release of TNF and interleukin-6 (IL-6) by purified B-cell chronic lymphocytic leukaemia (CLL) cells in vitro. TNF (100 U/ml) increased 3H-TdR uptake in cells to 700 +/- 302% of control (mean +/- S.E., n = 9, p = 0.033). Recombinant IL-4 (10 ng/ml) consistently inhibited DNA synthesis in all CLL patients studied. When added at the start of 5 day cultures, IL-4 inhibited both spontaneous (41 +/- 17% inhibition, n = 3) and TNF induced (46 +/- 5% inhibition, n = 9, p = 0.01) 3H-TdR uptake. Similar results were obtained when IL-4 was added after 48 h of culture. This effect of IL-4 was dose dependent. Inhibition was not related to clinical stage. IL-4 (whether added at T0 or T48h) also inhibited spontaneous release of TNF and IL-6 measured at 48 and 120 h. TNF and IL-4 had no consistent effect on normal cord blood CD5+ B-cells. These data show that IL-4 has inhibitory effects on B-CLL DNA synthesis and also inhibits spontaneous release of IL-6 and TNF in vitro. IL-4 may have a role in vivo in reducing proliferation in these B-cell malignancies by inhibiting potential autocrine growth loops.

Interleukin-2 receptor gamma chain: a functional component of the interleukin-4 receptor

The interleukin-2 (IL-2) receptor gamma chain (IL-2R gamma) is an essential component of high- and intermediate-affinity IL-2 receptors. IL-2R gamma was demonstrated to be a component of the IL-4 receptor on the basis of chemical cross-linking data, the ability of IL-2R gamma to augment IL-4 binding affinity, and the requirement for IL-2R gamma in IL-4-mediated phosphorylation of insulin receptor substrate-1. The observation that IL-2R gamma is a functional component of the IL-4 receptor, together with the finding that IL-2R gamma associates with the IL-7 receptor, begins to elucidate why deficiency of this common gamma chain (gamma c) has a profound effect on lymphoid function and development, as seen in X-linked severe combined immunodeficiency.

Cytokines and intracellular signals involved in the regulation of B-CLL proliferation

Cytokines play an important role in the regulation of both normal and malignant B cells. In this paper we give a brief overview of the major cytokines involved in the regulation of B-CLL proliferation. In vitro experiments have indicated that there is an antagonistic interaction between TNF-alpha as a growth-enhancing factor and IL-4, which inhibits the growth of B-CLL. We have extended these findings with recent experiments on the intracellular signals which might be involved in these processes. We show that increased levels of intracellular cAMP dose-dependently inhibit the TNF-alpha-induced proliferation of B-CLL. On the basis of these results, we propose a model for the signals involved in the regulation of B-CLL proliferation. The implications for possible new ways of treatment are discussed.

Interleukin 10 (IL-10) upregulates functional high affinity IL-2 receptors on normal and leukemic B lymphocytes

Interleukin 10 (IL-10) has recently been shown to induce normal human B lymphocytes to proliferate and differentiate into immunoglobulin (Ig)-secreting cells. Herein, we show that IL-10 also promotes DNA synthesis and IgM production by anti-CD40 activated B cell chronic lymphocytic leukemia (B-CLL). Most strikingly, IL-2 and IL-10 were found to synergize to induce the proliferation and differentiation of B-CLL cells. This synergy between IL-2 and IL-10 was also observed with normal B cells which proliferated strongly and secreted large amounts of IgM, IgG, and IgA. The observed synergy is likely to be due to the IL-10-induced increase of high affinity IL-2 receptors on both normal and leukemic B cells. This increase of high affinity receptor is associated to an increase of Tac/CD25 expression that can be detected by flow cytometric analysis. Taken together, these results indicate that IL-10 permits anti-CD40 activated B cells to respond to IL-2 through an induction of high affinity IL-2 receptors. This effect of IL-10 may partly explain how T cells, which activate B cells in a CD40-dependent fashion, induce B cell proliferation and differentiation mostly through IL-2.

Higher proliferative response in B-chronic lymphocytic leukemia (B-CLL) as compared to B-monoclonal lymphocytosis of undetermined significance (B-MLUS) after stimulation with Staphylococcus aureus and anti-CD40 monoclonal antibodies

B-CLL is a malignant monoclonal B-cell disorder and B-MLUS is the benign counterpart. The proliferative response and the capacity to secrete IgM was measured in B-CLL and B-MLUS, respectively, and compared to normal B-cells. SAC and a mAb against CD40 were used as stimulatory agents. No cell population responded to anti-CD40 mAb alone. SAC only induced a high DNA synthesis rate in normal B-cells as well as in B-CLL cells, although the magnitude was three-fold lower and delayed for about 48 h in B-CLL. B-MLUS cells did not proliferate in response to SAC. The combination of anti-CD40 and SAC enhanced the proliferative capacity of normal B-cells and produced a more rapid response in B-CLL. B-MLUS cells were not activated. Normal B-cells and B-MLUS did not secrete IgM after SAC stimulation, while B-CLL cells had a continuous increase in the IgM production during a 6-day culture period. The higher proliferative capacity of B-CLL cells compared with B-MLUS cells may be explained by an increased expression of activation molecules e.g. receptors for various cytokines and growth factors. Moreover, the inertness and inability of B-MLUS cells in comparison to normal B- and B-CLL cells to respond to powerful activation signals might indicate an intrinsic defect of B-MLUS cells in the signal transduction leading to a block of mitosis and a benign course of the disease.

Interleukin-4 (IL-4) enhances homotypic adhesion of activated B-chronic lymphocytic leukaemia (B-CLL) cells via a selective up-regulation of CD54

It is well established that cell-to-cell contact modifies cytokine signalling but little is known on the role of homotypic cell adhesion for proliferation and differentiation of B cells. Homotypic adhesion involves mainly the interaction between the adhesion molecules Leukocyte Function Antigen-1 (LFA-1) and its ligand CD54 (ICAM-1). A well-characterized B-chronic lymphocytic leukaemia (B-CLL) clone (I-83) was used as a source of monoclonal B cells inducible to DNA synthesis and differentiation by using 12-O-tetradecanoyl-phorbol-13-acetate (TPA) in combination with interleukin-4 (IL-4) and thioredoxin (Trx)-containing supernatant from a T-cell hybridoma (BSF-MP6). This paper shows that IL-4 alone was able to induce aggregation of B-CLL cells and to strongly enhance TPA+BSF-MP6-induced aggregation. The results from studying the expression of CD11a and CD18, the two subunits of LFA-1, and CD54 during stimulated DNA synthesis and differentiation suggest that IL-4-induced, or enhanced, aggregation was mainly mediated by a selective up-regulation of CD54. It was further demonstrated by antibody blockade to either CD11a, CD18 or CD54 that aggregation could be inhibited without affecting induced DNA synthesis or differentiation.

Diseases associated with HTLV-I: virus, IL-2 receptor dysregulation and redox regulation

HTLV-I, the etiological agent in adult T-cell leukemia, has also been strongly implicated in a number of non-neoplastic T-cell-associated diseases. Here, Junji Yodoi and Takashi Uchiyama review these associations and focus on the emerging concepts of IL-2R dysregulation and redox regulation by adult T-cell leukemia-derived factor in the pathogenesis of HTLV-I-related diseases.

Dysregulation of adult T-cell leukemia-derived factor (ADF)/thioredoxin in HIV infection: loss of ADF high-producer cells in lymphoid tissues of AIDS patients

Adult T-cell leukemia (ATL)-derived factor (ADF) is a multifunctional protein homologous to thioredoxin (TRX) with co-cytokine and thiol-dependent reducing activities. ADF/thioredoxin production is enhanced in T cells transformed by HTLV-I. We have examined the effect of HIV-1 infection on ADF/TRX expression using specific antibody against ADF/TRX. Lymph nodes from 5 AIDS and 1 AIDS-related complex (ARC) patients were examined. As a control, 8 HIV noninfected lymph nodes, including 3 cases with hyperplasia, were also examined. Immunohistopathological studies using normal HIV noninfected lymph nodes showed that ADF/TRX high-producer (ADFh) cells were macrophages and cells with dendritic morphology in the paracortical area. Abundant ADFh cells were observed in HIV noninfected hyperplastic lymph nodes. The number of ADFh cells was low in hyperplastic lymph nodes from an ARC patient. All of the lymph nodes of 5 AIDS cases were atrophic and the number of ADFh cells were extremely low. To verify these histochemical studies, we examined the effect of in vitro HIV infection on ADF/TRX expression in HTLV-I (+) T-cell lines. Western blot analysis showed that a reduction of ADF/TRX in HIV-1-infected SKT-1B and MT-2 cells, and the reduction inversely correlated with p24 antigen level. On the basis of the above in vivo and in vitro findings, we imply that the levels of ADF/TRX were down-regulated by HIV-1 infection and that the down-regulation may play a role for pathophysiology of HIV-infected individuals.

Tumor necrosis factor, but not other hematopoietic growth factors, prolongs the survival of hairy cell leukemia cells

In order to determine the growth factor requirements of hairy cell leukemia (HCL) cells, we studied the in vitro effects of tumor necrosis factor (TNF), interleukin (IL) 1 alpha, IL-1 beta, IL-2, IL-3, IL-4, IL-5, IL-6, B-cell growth factor (BCGF), GM-CSF, PHA-stimulated lymphocyte-conditioned media (CM), and 5637 bladder carcinoma CM on HCL cells obtained from spleens of patients with HCL. Mononuclear cells from a normal donor, obtained at post-traumatic splenectomy, served as a control. TNF prolonged the survival of HCL cells obtained from five different HCL patients when compared to cells cultured in control media alone, although cell proliferation could be demonstrated in only two of the five. HCL cells stained negative for the Epstein-Barr nuclear antigen (EBNA) both before and after 4 weeks in culture. BCGF, 5637 CM, and PHA-stimulated lymphocyte CM also prolonged the survival of HC25 and HC56 cells, although not to the same degree as TNF. Cells cultured in BCGF, however, stained positive for EBNA. None of the other recombinantly produced or purified cytokines prolonged the survival of the leukemic cells. With the exception of IL-2, none of the growth factors studied prolonged the survival of purified normal spleen (NS) cells over a 4-week period of time when compared to NS cells incubated in media alone. TNF prolonged the survival of HC25 cells in a dose-dependent manner, and a highly purified antibody to TNF abrogated the effects of TNF. HC25 cells incubated in the presence of control media alone did not constitutively produce TNF mRNA; however, incubation of the cells in the presence of TNF for 48 h induced the cells to express TNF message. We conclude that TNF is important in prolonging the survival of HCL cells, and thus may be important in the pathogenesis of this disease.

ADF (adult T cell leukemia-derived factor)/human thioredoxin and viral infection: possible new therapeutic approach

ADF (adult T-cell leukemia-derived factor), originally defined as an inducer of interleukin 2 receptor/alpha (IL-2R/alpha), is a homologue of thioredoxin. ADF is constitutively produced by human lymphoid cell lines transformed by human T-lymphotropic virus type I (HTLV-I) or Epstein-Barr virus (EBV). ADF augments the proliferation of HTLV-I and EBV transformed cells as an autocrine growth factor. These data are indicative of the possible involvement of ADF in virus-related transformation of cells and their autocrine growth. On the other hand, thioredoxin contains a redox active disulfide and has a reducing activity in the presence of thioredoxin reductase and NADPH. To clarify the role of ADF/thioredoxin system in the viral transformation, we tested the effect of 13-cis-retinoic acid (RA), which is a competitive inhibitor of thioredoxin reductase, on the growth of ADF high producing cells. The expression of IL-2R/alpha on HTLV-I (+) cells was suppressed by RA. RA dose-dependently reduced the cell number and viability of ADF high producing lymphoid cells. Moreover, it had a suppressive effect on the proliferation of ADF high producing cells. It is suggested that RA has an inhibitory effect on the activation and the growth of cells producing ADF and that inhibition of the ADF/thioredoxin system may be a new therapeutic approach for retrovirus-related disorders.

New modalities of therapy in chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is the most cormmon form of leukemia in adults in Western countries. After several decades of relative inactivity, important progress has been made in our understanding of the biology and immunology of this disorder. In addition, exciting therapeutic results have been achieved with several new, unique, and effective therapies. The most interesting chemotherapeutic agent is fludarabine, a purine analogue which achieves complete remission in 13% of relapsed or refractory patients and in greater than 30% of previously untreated patients; the overall response rates of 60% and 75%, respectively, are superior to reports with other single agents or combination regimens. Related drugs with promising activity are 2'-deoxycoformycin, and 2-chlorodeoxyadenosine. Preliminary studies are evaluating allogeneic and autologous bone marrow transplantation as potentially curative therapy. Biological approaches exploiting new insights into the immunology of CLL include the use of lymphoid growth factors. Interpretation of results of CLL studies has suffered from variability in eligibility and response criteria, especially definitions of complete remission. Recently published standardized guidelines for CLL clinical trials will facilitate comparisons among therapies and help identify those which are most promising. Continued progress will require integration of laboratory science and clinical investigation.

Interleukins 1, 4 and 6 induce the colony formation of human bone marrow B lineage cells

An agar-based, B cell colony assay (McGinnes, K. et al., Blood 1990. 76:896) has been used to study the influence of known cytokines on the growth of B lineage colonies initiated by cells from normal, human bone marrow samples. We demonstrate that a combination of interleukin (IL) 1, IL4 and IL6 act directly to promote the generation of plaque-forming colonies. IL6 was shown to act at a late stage of colony formation, which is consistent with its role in the induction of immunoglobulin secretion from mature B cells. In contrast, IL 1 and IL 4 were required at earlier stages in the formation of colonies containing cells which secrete immunoglobulin.

Crystallization and preliminary X-ray investigation of recombinant human interleukin 4

Crystals of recombinant human interleukin 4 have been grown from solutions of ammonium sulfate. The crystals are tetragonal, space-group P4(1)2(1)2 or P4(3)2(1)2; the unit cell axes are a = 92.2(1) A and c = 46.4(1) A. The crystals are stable to X-rays for at least three days and diffract beyond 2.8 A resolution. The crystals contain approximately 63% solvent, assuming there is one molecule in the asymmetric unit.

Characterization of B cell growth in systemic lupus erythematosus. Effects of recombinant 12-kDa B cell growth factor, interleukin 4 and transforming growth factor-beta

B cells from systemic lupus erythematosus (SLE) patients have been shown to be hyperactive as measured by proliferation and immunoglobulin production. We find that B cells from 6 of 13 SLE patients, in the absence of prior activation, respond two to three times better to recombinant 12-kDa B cell growth factor (BCGF) than do normal or rheumatoid arthritis B cells (p less than 0.005). B cells from normally responsive SLE patients require an anti-mu antibody activation step to generate similar proliferative signal in response to r12-kDa-BCGF. There are no clinical or serological parameters that distinguish these hyperresponsive SLE patients from the normally responsive SLE patients. The combination of r12-kDa-BCGF and interleukin 4 (IL4) gives an enhanced response with both normal and SLE B cells. Transforming growth factor type beta (TGF-beta) suppresses the response to r12-kDa-BCGF in a dose-dependent fashion using B cells from both healthy donors and SLE patients. We conclude that peripheral blood B cells are in an activated state (as detected by response to 12-kDa-BCGF) in approximately 50% of SLE patients. These B cells respond normally to regulation by IL4 and TGF-beta. A therapeutic approach aimed at reducing the B cell hyperactivity in SLE would involve suppressing the effects of 12-kDa-BCGF and IL4 while at the same time enhancing the effects of TGF-beta.

Dual effects of interleukin 4 on antigen-activated human B cells: induction of proliferation and inhibition of interleukin 2-dependent differentiation

We analyzed the effects of interleukin 2 (IL 2) and IL 4 isolated and in association on the specific response of human B cells triggered by trinitrophenylated polyacrylamide beads (TNP-PAA). IL 2 induced an increase (more than 10 times) in the number of hapten-binding cells [detected by a rosette-forming cell (RFC) assay] as well as the generation of antibody-producing cells [detected by a plaque-forming cell (PFC) assay]. IL 4 induced an isolated RFC response without PFC response. We verified that the IL 4 (as well as 12)-induced RFC were hapten specific and mediated through membrane IgM. Density fractionation experiments showed that IL 4-induced RFC were equally distributed between high-density and intermediate-density B cells. IL 2 appeared to drive more B cells into the intermediate density fraction. IL 2-induced PFC belonged to the RFC population and were intermediate-size B cells. IL 2 drove more RFC into an activated stage and it induced the differentiation of a number of them into antibody-producing cells. The evaluation of the proportion of RFC able to incorporate thymidine showed that both IL induced a substantial proliferation of antigen-activated B cells. However, IL 4 inhibited the IL 2-dependent PFC without affecting the number of RFC nor the proportion of proliferating RFC induced by this IL. These results directly demonstrate that human IL 4 triggers the expansion of antigen-activated B cells and selectively inhibits the IL 2-induced differentiation.

Immunophenotype of hairy-cell leukemia

15 cases of HCL were studied with a panel of monoclonal antibodies against different leukocyte antigens. A B-cell phenotype different from that of B-CLL was observed (CD10-, CD19+, CD20+, CD21-, CD22+, CD37+, CD38-, FMC7+, LN1+, PCA-1+, BLy7+ and CD5-). As expected, CD11c and CD25 were positive and, in addition, a My7 and My9 positivity in varying degree was noted. 3 weeks of in vitro incubation did not significantly alter the phenotype. We conclude that HCL exhibits a unique phenotype among chronic B-cell leukemias, which is closer to the plasma cell stage of differentiation than that of B-CLL. The BLy7 monoclonal antibody seems to be a promising marker for HCL.

In vitro transformation by Epstein-Barr virus induces a switch in growth factor and anti-IgM responsiveness in a human leukemic B cell clone

By in vitro transformation with Epstein-Barr virus (EBV), we have previously established EBV+ lymphoblastoid cell lines (LCL) from a patient with leukemic centrocytic B cell lymphoma. EBV-transformed LCL and EBV genome-negative leukemic B cells showed identical chromosome aberrations and IgH gene rearrangements. In the present study we have analyzed the effect of exogenous cytokines [interleukin (IL) 1, 2, 3, 4, 6, tumor necrosis factor, lymphotoxin, transforming growth factor beta, (TGF-beta)] and anti-IgM antibodies on the in vitro proliferation of EBV- leukemic B cells and EBV-converted LCL. In contrast to conventional chronic lymphocytic leukemia, B cells of the patient DUL spontaneously proliferated for up to two weeks in the absence of exogenous lymphokines. The spontaneous proliferative capacity of clonal DUL B cells was not modulated by IL 1, IL 3, IL 6, TNF or LT. In vitro growth of DUL B cells was increased, however, by exogenous recombinant (r)IL 2, and was abrogated by TGF-beta, rIL 4 and anti-IgM. rIL 4 not only inhibited spontaneous B cell proliferation but also neutralized the enhancing effect of rIL 2. In contrast, growth of the EBV-transformed DUL LCL was not affected by any of these factors. These data demonstrate that in vitro infection and transformation of a clonal B cell population by EBV induces a switch in responsiveness to rIL 4, TGF-beta and anti-IgM. In addition, this report is the first to demonstrate an inhibitory effect of rIL 4 on a spontaneously proliferating human leukemic B cell clone.