Interleukin-10 mRNA expression in B-cell chronic lymphocytic leukaemia inversely correlates with progression of disease

Interleukin-10 receptor signaling promotes the maintenance of a PD-1int TCF-1+ CD8+ T cell population that sustains anti-tumor immunity

T cell exhaustion limits anti-tumor immunity and responses to immunotherapy. Here, we explored the microenvironmental signals regulating T cell exhaustion using a model of chronic lymphocytic leukemia (CLL). Single-cell analyses identified a subset of PD-1^hi, functionally impaired CD8⁺ T cells that accumulated in secondary lymphoid organs during disease progression and a functionally competent PD-1^int subset. Frequencies of PD-1^int TCF-1⁺ CD8⁺ T cells decreased upon Il10rb or Stat3 deletion, leading to accumulation of PD-1^hi cells and accelerated tumor progression. Mechanistically, inhibition of IL-10R signaling altered chromatin accessibility and disrupted cooperativity between the transcription factors NFAT and AP-1, promoting a distinct NFAT-associated program. Low IL10 expression or loss of IL-10R-STAT3 signaling correlated with increased frequencies of exhausted CD8⁺ T cells and poor survival in CLL and in breast cancer patients. Thus, balance between PD-1^hi, exhausted CD8⁺ T cells and functional PD-1^int TCF-1⁺ CD8⁺ T cells is regulated by cell-intrinsic IL-10R signaling, with implications for immunotherapy.

Impact of Immune Parameters and Immune Dysfunctions on the Prognosis of Patients with Chronic Lymphocytic Leukemia

Simple Summary

In chronic lymphocytic leukemia (CLL), immune alterations—affecting both the innate and adaptive immunity—are very common. As a clinical consequence, patients with CLL frequently present with autoimmune phenomena, increased risk of infections and second malignancies. The aim of this review article is to present available data on CLL-associated alterations of immune parameters that correlate with known prognostic markers and with clinical outcome. Also, data on the impact of immune-related clinical manifestations on the prognosis of patients with CLL will be discussed.

Abstract

Chronic lymphocytic leukemia (CLL) is characterized by a wide spectrum of immune alterations, affecting both the innate and adaptive immunity. These immune dysfunctions strongly impact the immune surveillance, facilitate tumor progression and eventually affect the disease course. Quantitative and functional alterations involving conventional T cells, γδ T cells, regulatory T cells, NK and NKT cells, and myeloid cells, together with hypogammaglobulinemia, aberrations in the complement pathways and altered cytokine signature have been reported in patients with CLL. Some of these immune parameters have been shown to associate with other CLL-related characteristics with a known prognostic relevance or to correlate with disease prognosis. Also, in CLL, the complex immune response dysfunctions eventually translate in clinical manifestations, including autoimmune phenomena, increased risk of infections and second malignancies. These clinical issues are overall the most common complications that affect the course and management of CLL, and they also may impact overall disease prognosis.

Clinico-Biological Implications of Modified Levels of Cytokines in Chronic Lymphocytic Leukemia: A Possible Therapeutic Role

B-cell chronic lymphocytic leukemia (B-CLL) is the main cause of mortality among hematologic diseases in Western nations. B-CLL is correlated with an intense alteration of the immune system. The altered functions of innate immune elements and adaptive immune factors are interconnected in B-CLL and are decisive for its onset, evolution, and therapeutic response. Modifications in the cytokine balance could support the growth of the leukemic clone via a modulation of cellular proliferation and apoptosis, as some cytokines have been reported to be able to affect the life of B-CLL cells in vivo. In this review, we will examine the role played by cytokines in the cellular dynamics of B-CLL patients, interpret the contradictions sometimes present in the literature regarding their action, and evaluate the possibility of manipulating their production in order to intervene in the natural history of the disease.

Restoring the functional immunogenicity of chronic lymphocytic leukemia using epigenetic modifiers

Chronic lymphocytic leukemia (CLL) is a malignancy arising from immune cells (B-lymphocytes) endowed with intrinsic antigen-presenting capabilities. Such a function however is lost during malignant transformation and CLL cells are well known for their inability to process and present antigens to the T-cell arm of the immune system. Instead, malignant CLL cells elicit a vast array of immune regulatory mechanisms conducive to T-cell dysfunction and immunosuppression. Previously, we have shown that treatment of CLL cells with the demethylating agent 5-aza-2'-deoxycytidine unleashed target antigen expression. Here we show for the first time that combining two epigenetic modifiers, 5-aza-2'-deoxycytidine and the histone deacetylase inhibitor LAQ824 effectively restores the immunogenicity of CLL cell lines as well as primary cells obtained from CLL patients. Indeed, such a combination induces the expression of novel and highly antigenic cancer-testis antigens (CTAs) and costimulatory molecules. These changes facilitate the formation of robust supramolecular activation complexes (SMAC) between CLL cells and responder T-cells leading to intracellular signaling, lytic granule mobilization, and polarization of functional and relevant T-cell responses. This cascade of T-cell activating events triggered by CLL cells with restored APC function, points to combined epigenetic modifier treatment as a potential immunotherapeutic strategy for CLL patients.

Loss of tissue expression of interleukin-10 promotes the disease progression of colorectal carcinoma

PURPOSE

Interleukin-10 (IL-10) is a unique cytokine that is thought to be a potent immunostimulatory and immunosuppressive factor. The aim of this study was to investigate IL-10 expression in colorectal cancer, and clarify its relationship to the clinicopathological findings and prognosis.

METHODS

Tissue samples were collected from 92 patients with colorectal cancer and adjacent normal mucosa. The expression of IL-10 in colorectal cancer tissues was evaluated by immunohistochemistry. Tissue levels of IL-10 were measured by enzyme-linked immunosorbent assay.

RESULTS

The mean concentration of IL-10 did not significantly differ between the cancer tissue and adjacent normal mucosa. The IL-10 concentration in cancer tissue with positive staining immunohistochemically was significantly higher than that without IL-10 staining. The IL-10 level in cancer tissue decreased in accordance with advanced-stage serosal invasion and lymph node involvement, and thus predicted poor survival in patients undergoing surgery with curative intent. A Cox multivariate analysis demonstrated that a decreased IL-10 level in cancer tissue was an independent risk factor for poor survival.

CONCLUSION

The tumor IL-10 level in colorectal cancer was inversely correlated with serosal invasion and lymph node metastasis, which thus reflected tumor progression. Evaluating the tumor expression of IL-10 may therefore provide valuable information for predicting the long-term survival in patients undergoing surgery with curative intent.

Effects of Preactivated Autologous T Lymphocytes on CD80, CD86 and CD95 Expression by Chronic Lymphocytic Leukemia B Cells

Profound immune dysfunction is a constant feature in B-cell chronic lymphocytic leukemia (B-CLL) patients. Immunological abnormalities include hypogammaglobulinemia, impaired immunoglobulin class switching and diminished germinal center formation. This state of immune suppression renders B-CLL patients highly susceptible to infections, which contribute greatly to morbidity and mortality in this disease. Impaired T cell function in B-CLL is well-documented and has been suggested to result from inhibitory effects exerted by malignant B lymphocytes. Because the presence of leukemic cells may represent a major obstacle to efficient T cell activation, T lymphocytes were separated from CLL B cells, stimulated with phorbol 12-myristate 13-acetate (PMA) and ionomycin for 4h, and then cocultured with autologous leukemic B cells both at a 1:1 ratio or at the same ratio as in vivo for 24-40 h. CLL B cell expression of CD86 and CD95 was markedly upregulated using this approach, whereas CD80 expression was augmented only in a minority of patients; these effects were partially preserved even when preactivated T cells were rechallenged with CLL B cells at the same low T/B cell ratio as that observed in vivo. Finally, CD80 upregulation on CLL B cells appeared to be mainly dependent on CD40L-mediated stimulation, whereas CD86 and CD95 expression was efficiently augmented by soluble factors released by preactivated T lymphocytes. In conclusion, efficient activation of T lymphocytes in B-CLL may be achieved which, in turn, may result in enhanced antigen-presenting capacity and susceptibility to apoptosis of leukemic cells via CD86 and CD95 upregulation, respectively.

Expression of soluble CD27 and interleukins-8 and -10 in B-cell chronic lymphocytic leukemia: correlation with disease stage and prognosis

Investigators in this study explored levels of soluble CD27 (sCD27), interleukin (IL)-8, and IL-10 in B-cell chronic lymphocytic leukemia (B-CLL), and the correlation of these levels with disease stage and prognosis. Plasma IL-8, IL-10, and sCD27 levels were assessed with enzyme-linked immunosorbent assay tests in 22 healthy donors and 70 patients with B-CLL (49 men and 21 women). Mean patient age was 61.57 y (range, 44-75 y). Mean healthy donor age was 62.09 y (range, 40-72 y). In the study group, mean values were as follows: plasma IL-8, 284.758 pg/mL (0-1000 pg/mL) plasma IL-10, 26.152 pg/mL (0-100 pg/mL) sCD27, 731.357 U/mL (139.9-1000 U/mL) white blood cell count, 59.9 x 10(9)/L (0.8-250.0 x 10(9)/L) hemoglobin count, 11.2 g/dL (5.0-16.2 g/dL) platelet count, 162.5 x 10(9)/L (29.8-317 x 10(9)/L) B(2) microglobulin (B(2)M) 3350.2 mg/L (274.7-7499.9 mg/L) CD38, 19.5% and lactate dehydrogenase (count, 497.5 U/L (263.0-1507 U/L). Patients represented all Rai stages, with 22.9% at stage 0, 11.4% at stage I, 11.4% at stage II, 41.4% at stage III, and 12.9% at stage IV. Plasma levels of IL-8, IL-10, and sCD27 were correlated between study and control groups; significantly higher IL-8 (P=.001) and sCD27 (P=.000) levels were found, but the IL-10 level was not significant (P=.139). Plasma IL-10 (P=.01) and sCD27 (P=.008) were positively correlated with Rai stage, but IL-8 was not (P=.146). Levels of sCD27 were significantly correlated with values for B2M (P=.000), hemoglobin (P=.028), lactate dehydrogenase (P=.001), CD19 (P=.03), and IL-10 (P=.000). IL-8 was significantly correlated with white blood cell (P=.000) count, and CD38 (P=.001) and CD5 (P=.006) levels. IL-10 was significantly correlated with B(2)M (P=.017), CD19 (P=.000), platelet (P=.002), and CD27 (P=.000). In survival distributions for CD27, IL-8 and IL-10 were found to have more significant relationships for all parameters (P=.0000). In conclusion, the authors suggest that sCD27, IL-8, and IL-10 are more significant prognostic factors for B-CLL when compared with others, and these values should correlate with new prognostic factors (eg, zeta-associated protein-70, mutated/unmutated immunoglobulin variable heavy chain).

Interleukin-10-secreting type 1 regulatory T cells in rodents and humans

Interleukin-10 (IL-10)-secreting T regulatory type 1 (Tr1) cells are defined by their specific cytokine production profile, which includes the secretion of high levels of IL-10 and transforming growth factor-beta(TGF-beta), and by their ability to suppress antigen-specific effector T-cell responses via a cytokine-dependent mechanism. In contrast to the naturally occurring CD4+ CD25+ T regulatory cells (Tregs) that emerge directly from the thymus, Tr1 cells are induced by antigen stimulation via an IL-10-dependent process in vitro and in vivo. Specialized IL-10-producing dendritic cells, such as those in an immature state or those modulated by tolerogenic stimuli, play a key role in this process. We propose to use the term Tr1 cells for all IL-10-producing T-cell populations that are induced by IL-10 and have regulatory activity. The full biological characterization of Tr1 cells has been hampered by the difficulty in generating these cells in vitro and by the lack of specific marker molecules. However, it is clear that Tr1 cells play a key role in regulating adaptive immune responses both in mice and in humans. Further work to delineate the specific molecular signature of Tr1 cells, to determine their relationship with CD4+ CD25+ Tregs, and to elucidate their respective role in maintaining peripheral tolerance is crucial to advance our knowledge on this Treg subset. Furthermore, results from clinical protocols using Tr1 cells to modulate immune responses in vivo in autoimmunity, transplantation, and chronic inflammatory diseases will undoubtedly prove the biological relevance of these cells in immunotolerance.

Fibromodulin, an extracellular matrix protein: characterization of its unique gene and protein expression in B-cell chronic lymphocytic leukemia and mantle cell lymphoma

Fibromodulin is an extracellular matrix protein normally produced by collagen-rich tissues; the fibromodulin gene has been found to be the most overexpressed gene in B-cell chronic lymphocytic leukemia. In this study, fibromodulin was expressed at the gene level (reverse transcription-polymerase chain reaction [RT-PCR]) in all patients with B-CLL (n = 75) and in most (5 of 7) patients with mantle cell lymphoma (MCL). No mutations in the fibromodulin gene were detected. Fibromodulin was also detected at the protein level in the cytoplasm of the B-CLL cells and in the supernatant after in vitro cultivation, but not at the cell surface. Fibromodulin was not found in patients with T-cell chronic lymphocytic leukemia (T-CLL), B-cell prolymphocytic leukemia (B-PLL), T-cell prolymphocytic leukemia (T-PLL), hairy cell leukemia, follicular lymphoma, lymphoplasmacytic lymphoma, multiple myeloma, acute lymphoblastic leukemia (ALL), acute myelogenous leukemia (AML), or chronic myelogenous leukemia (CML) or in 36 hematologic cell lines. Normal blood mononuclear cells (T and B lymphocytes, monocytes), tonsil B cells, and granulocytes did not express fibromodulin. Activation (phorbol 12-myristate 13-acetate [PMA]/ionomycin) of normal T and B lymphocytes induced weak fibromodulin gene expression, but not to the extent seen in freshly isolated B-CLL cells. The reason for the exclusive ectopic expression of fibromodulin in B-CLL and MCL is unknown. However, its unique protein expression makes it likely that fibromodulin is involved in the pathobiology of B-CLL and MCL. (Blood. 2005;105:4828-4835)

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.

Interleukin-10 therapy--review of a new approach

Interleukin (IL)-10 is an important immunoregulatory cytokine produced by many cell populations. Its main biological function seems to be the limitation and termination of inflammatory responses and the regulation of differentiation and proliferation of several immune cells such as T cells, B cells, natural killer cells, antigen-presenting cells, mast cells, and granulocytes. However, very recent data suggest IL-10 also mediates immunostimulatory properties that help to eliminate infectious and noninfectious particles with limited inflammation. Numerous investigations, including expression analyses in patients, in vitro and animal experiments suggest a major impact of IL-10 in inflammatory, malignant, and autoimmune diseases. So IL-10 overexpression was found in certain tumors as melanoma and several lymphomas and is considered to promote further tumor development. Systemic IL-10 release is a powerful tool of the central nervous system to prevent hyperinflammatory processes by activation of the neuro-endocrine axis following acute stress reactions. In contrast, a relative IL-10 deficiency has been observed and is regarded to be of pathophysiological relevance in certain inflammatory disorders characterized by a type 1 cytokine pattern such as psoriasis. Recombinant human IL-10 has been produced and is currently being tested in clinical trials. This includes rheumatoid arthritis, inflammatory bowel disease, psoriasis, organ transplantation, and chronic hepatitis C. The results are heterogeneous. They give new insight into the immunobiology of IL-10 and suggest that the IL-10/IL-10 receptor system may become a new therapeutic target.

B-chronic lymphocytic leukemia: practical aspects

B-CLL is the most common adult leukemia in the Western world. It is a neoplasia of mature looking B-monoclonal lymphocytes co-expressing the CD5 antigen (involving the blood, the bone marrow, the lymph nodes and related organs). Much new information about the nature of the neoplastic cells, including chromosomal and molecular changes as well as mechanisms participating in the survival of the leukemic clone have been published recently, in an attempt to elucidate the biology of the disease and identify prognostic subgroups. For the time being, clinical stage based on Rai and Binet staging systems remains the strongest predictor of prognosis and patients' survival, and therefore it affects treatment decisions. In the early stages treatment may be delayed until progression. When treatment is necessary according to well-established criteria, there are nowadays many different options. Chlorambucil has been the standard regimen for many years. During the last decade novel modalities have been tried with the emphasis on fludarabine and 2-chlorodeoxyadenosine and their combinations with other drugs. Such an approach offers greater probability of a durable complete remission but no effect on overall survival has been clearly proven so far. Other modalities, included in the therapeutic armamentarium, are monoclonal antibodies, stem cell transplantation (autologous or allogeneic) and new experimental drugs. Supportive care is an important part of patient management and it involves restoring hypogammaglobulinemia and disease-related anemia by polyvalent immunoglobulin administration and erythropoietin respectively.

Interleukin-10 and the interleukin-10 receptor

Interleukin-10 (IL-10), first recognized for its ability to inhibit activation and effector function of T cells, monocytes, and macrophages, is a multifunctional cytokine with diverse effects on most hemopoietic cell types. The principal routine function of IL-10 appears to be to limit and ultimately terminate inflammatory responses. In addition to these activities, IL-10 regulates growth and/or differentiation of B cells, NK cells, cytotoxic and helper T cells, mast cells, granulocytes, dendritic cells, keratinocytes, and endothelial cells. IL-10 plays a key role in differentiation and function of a newly appreciated type of T cell, the T regulatory cell, which may figure prominently in control of immune responses and tolerance in vivo. Uniquely among hemopoietic cytokines, IL-10 has closely related homologs in several virus genomes, which testify to its crucial role in regulating immune and inflammatory responses. This review highlights findings that have advanced our understanding of IL-10 and its receptor, as well as its in vivo function in health and disease.

Over-expression of the functional interleukin-11 alpha receptor in the development of B-cell chronic lymphocytic leukemia

Several cytokines have been found to play a role in the pathogenesis of B-CLL. In the present study using reverse-transcriptase polymerase chain reaction (RT-PCR), FACS analysis and immunofluorescence we have shown the constitutive expression of IL-11 and IL-11R alpha in B-chronic lymphocytic leukemia (B-CLL). The expression level of IL-11R alpha in B-CLL cells is much higher than in PBL of normal donors. Recombinant human IL-11 (rhIL-11) activates B-CLL cells, leading to morphologic alterations of the cells and increase in cell number and size. Short-term cultivation in the presence of rhIL-11 did not lead to quantitative changes in the ratio of the living vs apoptotic and dead cells. However, in contrast to rhIL-6, pretreatment with rhIL-11, did not cause B-CLL cells to be resistant to the action of dexamethasone. These data suggest an essential role for the IL-11/IL11 R alpha system in the pathogenesis of the malignant B-CLL cells.

Reduced susceptibility to apoptosis correlates with kinetic quiescence in disease progression of chronic lymphocytic leukaemia

The role of apoptosis and cell kinetics in the mechanisms of disease progression of chronic lymphocytic leukaemia (CLL) is still unclear. In the present study, we investigated the susceptibility of leukaemic cells taken from 75 CLL patients with either stable (STD) or progressive disease (PRD) to enter apoptosis. Particular attention was paid to the relationship between cell cycle status and autologous serum (AS). The susceptibility to enter apoptosis was significantly greater in STD than in PRD, both in standard medium (mean = 23.62% +/- 14.7 versus 14.23% +/- 7.2; P = 0.02) and in the presence of AS (mean = 23.03% +/- 17.9 versus 11.27% +/- 7.6; P = 0.01). Furthermore, cell kinetics studies revealed a higher quiescence in PRD than in STD cases, both in terms of a lower RNA content (P = 0.04) and of higher expression of the negative cell cycle regulator p27kip1 (P = 0.03). These kinetic differences were confirmed by short-term in vitro culture both in fetal calf serum and in AS. The results of this study indicate that CLL cells from PRD cases are characterized by a higher degree quiescence and much lower susceptibility to apoptosis when compared with STD ones. In this context, AS does not appear to play a specific role. The association between these kinetic characteristics and disease progression in CLL prompts further studies to establish whether higher quiescence may be responsible for the decreased susceptibility of PRD cells to enter apoptosis.

Autologous antileukemic immune response induced by chronic lymphocytic leukemia B cells expressing the CD40 ligand and interleukin 2 transgenes

Although the B cells of chronic lymphocytic leukemia (B-CLL cells) express both tumor-specific peptides and major histocompatibility complex (MHC) class I antigens, they lack the capacity for costimulatory signaling, contributing to their protection against host antitumor immunity. To stimulate CLL-specific immune responses, we sought to transfer the human CD40 ligand (hCD40L) gene to B-CLL cells, using an adenoviral vector, in order to upregulate costimulating factors on these cells. Because efficient gene transduction with adenoviral vectors requires the expression of virus receptors on target cells, including the coxsackievirus B-adenovirus receptors (CAR) and alpha(v) integrins, we cocultured B-CLL cells with human embryonic lung fibroblasts (MRC-5 line). This exposure led to increased expression of integrin alpha(v)beta3 on B-CLL cells, which correlated with higher transduction rates. Using this novel prestimulation system, we transduced B-CLL cells with the hCD40L gene. The Ad-hCD40L-infected cells had higher expression of B7 molecules and induced activation of autologous T cells in vitro, but these T cells could not recognize parental leukemic cells. By contrast, an admixture of Ad-hCD40L-positive cells and leukemic cells transduced with the human interleukin 2 (IL-2) gene produced greater T cell activation than did either immunostimulator population alone. Importantly, this combination generated autologous T cells capable of specifically recognizing parental B-CLL cells. These findings suggest that the combined use of genetically modified CD40L-expressing B-CLL cells in combination with IL-2-expressing B-CLL cells may induce therapeutically significant leukemia-specific immune responses.

Interleukin-10 and the Interleukin-10 Receptor

Interleukin-10 (IL-10), first recognized for its ability to inhibit activation and effector function of T cells, monocytes, and macrophages, is a multifunctional cytokine with diverse effects on most hemopoietic cell types. The principal routine function of IL-10 appears to be to limit and ultimately terminate inflammatory responses. In addition to these activities, IL-10 regulates growth and/or differentiation of B cells, NK cells, cytotoxic and helper T cells, mast cells, granulocytes, dendritic cells, keratinocytes, and endothelial cells. IL-10 plays a key role in differentiation and function of a newly appreciated type of T cell, the T regulatory cell, which may figure prominently in control of immune responses and tolerance in vivo. Uniquely among hemopoietic cytokines, IL-10 has closely related homologs in several virus genomes, which testify to its crucial role in regulating immune and inflammatory responses. This review highlights findings that have advanced our understanding of IL-10 and its receptor, as well as its in vivo function in health and disease.

The levels of TNF alpha, IL4 and IL10 production by T-cells in B-cell chronic lymphocytic leukaemia (B-CLL)

Tumour necrosis factor alpha (TNF alpha), interleukin (IL) 4 and IL10 are important for the growth and survival of the leukaemic cells in B-cell chronic lymphocytic leukaemia (B-CLL). The present study investigates the production of TNF alpha, IL4 and IL10 in patients with B-CLL. Significant increases in the TNF alpha and IL4 mean levels compared to normal control CD2(+)-cells were observed for B-CLL lymphocytes (TNF alpha: P=0.0004 and IL4: P=0.0026). By contrast, the mean level of IL10 produced by purified B-CLL CD2(+)-cells was significantly lower than that seen with normal control T-cells (P=0.0136). No significant difference in the percentage (%) of T-cells that expressed cytoplasmic TNF alpha, IL4 and IL10 was observed between B-CLL and normal T-cells. However, a significant increase in the mean level of intracellular TNF alpha and IL4 expression was observed in B-CLL compared with normal control T-cells (TNF alpha: P=0.031; IL4: P=0.0027). The increased expression of cytoplasmic TNF alpha and IL4 appeared to be associated with increased cytokine production in the tested samples. The differences observed with some B-CLL cases in the production of TNF alpha, IL4 and IL10 by peripheral blood T-cells may suggest survival mechanisms for the leukaemic cells in these patients.

Characterization of cytokine, growth factor receptor, costimulatory and adhesion molecule expression patterns of bone marrow blasts in relapsed childhood B cell precursor all

Relapse of childhood acute lymphoblastic leukaemia (ALL) comprises a leading challenge of investigation. Characterization of leukaemic cells regarding their potency to express growth factors and surface molecules can provide insight into their aberrant biology. Thus, we analyzed bone marrow blasts from 10 children with relapsed B cell precursor ALL. The gene and protein expression of essential haematopoietic growth factors (IL-2, IL-4, IL-7, IL-10, IL-15, IFN-gamma, G-CSFR), their corresponding receptors as well as the expression pattern of adhesion molecules (ICAM-1, CD58) and costimulatory proteins (CD40, CD40L, B7.1, B7.2, CD28, MHC-I and II) was analyzed by RT-PCR and flow cytometry. Constitutive gene expression was found for IL-7, IL-10, IL-15 and IFN-gamma and their corresponding receptors. Flow-cytometric analysis showed that IL-10R, IL-7Ralpha, IL-4Ralpha and the gamma(c)chain are constitutively expressed, and that some cells bear the G-CSFR. IL-10 and IL-15 protein-producing leukaemic cells were easily detectable. The neoplastic cells mainly lack B7.1, and ICAM-1 is mostly decreased. Furthermore, high CD40, and, surprisingly, CD40L expression could be found. These studies show that ALL cells are likely to be sensitive to many growth factors and some factors are produced by the neoplastic cell itself. The secretion of IL-10 by leukaemic cells, and the absence or downregulation of conventional adhesion and costimulatory molecules might represent an effective mechanism of escape of immune surveillance in relapsed ALL.

The cAMP signaling pathway as a therapeutic target in lymphoid malignancies

Certain subsets of lymphoid cells, such as thymocytes or peripheral B cells, undergo apoptosis after treatment with agents which elevate intracellular 3',5' cyclic adenosine monophosphate (cAMP). Investigators have also noted induction of apoptosis of chronic lymphocytic leukemia (CLL) cells following treatment with methylxanthines, a phenomenon that may, at least in part, be due to the activity of these drugs as non-specific phosphodiesterase (PDE) inhibitors. We discuss three general strategies for altering cAMP-mediated signal transduction in lymphoid cells. After a review of what is known about the expression and regulation of PDE families in human lymphoid cells, we focus on the use of isoform-specific PDE inhibitors as potential therapeutic agents in CLL. Our work has suggested that despite the presence of PDE1, PDE3B, PDE4 and PDE7 enzymes in CLL, inhibition of PDE4 results in uniquely potent induction of apoptosis in CLL cells. This effect is relatively specific as comparable treatment of human peripheral blood T cells does not induce apoptosis. Clinical trials utilizing PDE4 inhibitors are indicated in the therapy of CLL patients resistant to standard therapy.

Accessory cells, cytokine loops and cell-to-cell interactions in chronic lymphocytic leukemia

In addition to the extensive work that has been conducted in order to understand better the biological features of the leukemic population in B-cell chronic lymphocytic leukemia (CLL), over the years considerable interest has been directed towards other related studies that may have important implications for the accumulation of the leukemic clone and for the immunoparesis typical of this disease. In the present review article, we discuss some of these areas of investigation and, in particular, we focus on: (1) the multiple abnormalities recorded within the T and cytotoxic compartment of patients with CLL; (2) cytokine loops occurring in this disease, with particular emphasis on the cytokines that appear to play a more critical role; and (3) the cell-to-cell cross talk that may be actively operational in CLL. These findings will be discussed in relation with the possible implications that each of them have in the expansion and clinical behavior of a disease that is increasingly proving its heterogeneity.

Cytokine expression in B-CLL in relation to disease progression and in vitro activation

Earlier, we reported an association between low in vitro and in vivo IL-1 and IL-6 production, decreased IL-1beta and IL-10 mRNA expression and B cell chronic lymphocytic leukemia (B-CLL) disease progression. We have now further investigated cytokine mRNA transcription in B-CLL cells and cytokine serum levels in B-CLL patients. Reverse transcriptase polymerase chain reaction (RT-PCR) amplification of tumor necrosis factor (TNFalpha), IFNgamma, IL-6 and BCGF was equally often seen in non-progressive and progressive patients. However, 4 out of 23 non-progressive cases expressed mRNA for IL-12 while no IL-12 expression was seen in 15 progressive patients. No IL-12 was found in sera or supernatants from in vitro stimulated B-CLL cells, whereas TNFalpha and IL-10 were detected in sera from 51 and 31 of 65 B-CLL patients, respectively. TNFalpha values were significantly high in sera from patients in stages III and IV with disease progression. TNFalpha and IL-10 were also detected in culture supernatants from in vitro stimulated B-CLL cells, whereas IFNgamma was undetectable in these cultures and rarely positive in serum. Although further investigations are required, our data and that from previous reports indicate that B-CLL-derived cytokines are involved in B-CLL disease progression.

Serum levels of tetranectin, intercellular adhesion molecule-1 and interleukin-10 in B-chronic lymphocytic leukemia

BACKGROUND AND OBJECTIVE

The fibrinolytic regulator tetranectin (TN), in association with the circulating intercellular adhesive molecule-1 (cICAM-1) and interleukin -10 (IL-10), may be involved in the metastatic cascade of B-chronic lymphocytic leukemia (B-CLL). Our aim was to investigate the potential usefulness of these molecules as prognostic markers in B-CLL.

DESIGN AND METHODS

Therefore, TN, cICAM-1, and IL-10 were assessed (ELISA) in the serum of 53 B-CLL patients, classified in Binet A, B, and C stages in comparison with those in 45 healthy subjects (HS).

RESULTS

TN was significantly lower in B-CLL patients than in HS (9.63 [8.75-11.51] mg/L, 13.75 [12.56-14.64] ng/mL, respectively, p<10(-5)), being lower (p = 0.05) in B and C stage patients (subgroup B+C) than in A stage ones (subgroup A). cICAM-1 levels were significantly higher in B-CLL patients than in HS (475.86 [355.86-593.79] ng/mL vs. 225.62 [118.49-312.83] ng/mL, respectively, p<10(-5)) with a tendency for higher levels in subgroup B+C than in subgroup A. A significant correlation of cICAM-1 with lactate dehydrogenase (LDH) (r(s) = 0.532, p = 0.049), and a significant increase in cICAM-1 in B-CLL with diffuse bone marrow infiltration (BMI) compared to that in B-CLL with nondiffuse BMI (624.48 [557.24-726.55] ng/mL vs. 480.34 [368.96-590.34] ng/mL, respectively, p = 0.0172) were found. A significant negative correlation between TN and cICAM-1 (r = -0.5017, p = 0.0001) was observed. IL-10 was detected in all B-CLL patients and in no HS (7.37 [5.30-10.55] pg/mL), being higher (p = 0.0153) in C than in A stage patients. A significant correlation of IL-10 with TN and cICAM-1 in subgroup B+C (r(s) = -0.659 [p = 0.014] and r = 0.679 [p = 0.011], respectively) was found.

CONCLUSIONS

The abovementioned findings and good performance characteristics of TN and cICAM-1 in B-CLL suggest the potential usefulness of these adhesive/recognition molecules as prognostic markers in B-CLL. The implication of these molecules along with IL-10 in the disease process deserves further study.

B-cell chronic lymphocytic leukemia: a bird of a different feather

PURPOSE

To review the recent major advances in the molecular and cell biology of B-cell chronic lymphocytic leukemia (B-CLL).

METHODS

We analyzed the nature of malignant B-CLL B cells and their interactions with the microenvironment.

RESULTS

B-CLL is a malignancy of a mantle zone-based subpopulation of anergic, self-reactive, activated CD5+ B cells devoted to the production of polyreactive natural autoantibodies. It is the quintessential example of a human malignancy that primarily involves defects in the induction of programmed cell death. An abnormal karyotype is observed in about 50% of patients with B-CLL. Patients with 13q14 abnormalities show heavy somatic mutation and have a benign disease. Trisomy 12 is associated with unmutated VH genes, atypical cellular morphology, and progressive disease. Extended cell survival is further shielded by a kinetic refractoriness likely promoted by abnormalities of the B-cell antigen receptor complex and favored by some cytokines that highlight a reciprocal dialog between malignant B and T cells. Because the tumor cells act as the major accessory cells, the accumulating malignant B-cell population per se is a hurdle to the production of normal antibodies and leads to a progressive and severe hypogammaglobulinemia. Conceivably, in the presence of certain immunoglobulin genes and when the T-cell control becomes deficient, activated malignant B cells may become able to present self-antigens and drive residual normal B cells to produce polyclonal autoantibodies restricted to self-antigens expressed only by blood cells and cause autoimmune cytopenias.

CONCLUSION

The distinctiveness of B-CLL B cells explains why B-CLL is different from other B-cell tumors and accounts for the development of immune deficiency and autoimmunity.

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.

Requirement for increased IL-10 in the development of B-1 lymphoproliferative disease in a murine model of CLL

Malignant B-1 cells derived from NZB mice, a murine model of spontaneous autoimmunity and B cell lymphoproliferative disease, produce significantly higher levels of IL-10 mRNA than normal B-1 or B cells. IL-10 may act as an autocrine growth factor for the expansion of malignant B-1 cells. In order to determine if elevated endogenous production of IL-10 was a required element for the malignant transformation of B-1 cells in NZB mice, backcross animals were studied for the linkage between elevated IL-10 expression and the presence of lymphoid malignancy. The phenotypes of aged (NZB x DBA/2)F1 x NZB animals were determined and a strong correlation was found between the elevated levels of IL-10 mRNA and the development of B-1 malignant clones. In contrast, an increased level of IL-10 message was not associated with elevated serum IgM or the presence of anemia or reticulocytosis which is mainly seen in response to autoantibody production. These results indicate that, at least in NZB, the autoimmunity and lymphoproliferation phenotypes are not linked genetically. IL-10 may enhance proliferation and the development of B-1 cell malignancy rather than antibody production by the B-1 cell subpopulation. Thus, IL-10 plays an important role in B-1 malignancies, and downregulation of IL-10 could be a likely site for intervention in B cell malignancies.