Interleukin-21 (IL-21

The clonal expansion of chronic lymphocytic leukemia (CLL) cells requires the interaction with the microenvironment and is under the control of several cytokines. Here, we investigated the effect of IL-15 and IL-21, which are closely related to IL-2 and share the usage of the common ␥ chain and of its JAK3-associated pathway. We found remarkable differences in the signal transduction pathways activated by these cytokines, which determined different responses in CLL cells. IL-15 caused cell proliferation and pre- IntroductionChronic lymphocytic leukemia (CLL), the most common leukemia in adults, is characterized by the progressive accumulation of CD5 ϩ neoplastic B cells, 1-3 which results from a dynamic balance between cell death and proliferation. 3,4 The finding that purified CLL cells do not proliferate and tend to undergo spontaneous apoptosis in vitro suggests that factors inducing CLL cell survival and proliferation might be present in the microenvironment of lymphoid organs or of the bone marrow. 5,6 Several cytokines such as the TNF family members BAFF and APRIL, 7,8 the chemokine SDF-1, 9,10 and interleukin-2 (IL-2) 11,12 and IL-15 13 stimulate CLL cell proliferation and/or survival in vitro. IL-2 and IL-15 share the usage of the IL-2R␤ (CD122) and of the common ␥ chain (␥ c ; CD132) 14,15 and thus have similar functional effects on IL-2R␤/␥ c ϩ cells. 16,17 The IL-2R␤ and ␥ c chains signal through the JAK1 and JAK3 tyrosine kinases, which activate downstream STAT pathways. 18,19 In addition to the IL-2R␤/␥ c complex, specific 21 molecules are required for high-affinity binding of each cytokine. Unlike IL-2R␣, IL-15R␣ is a high-affinity receptor also when expressed as an isolated chain, and is present on both lymphoid and nonlymphoid cell types. 20,21 IL-15R␣ is crucial for IL-15 activity, since both IL-15-and IL-15R␣-deficient mice display similar defects in the development of natural killer (NK) cells, of intraepithelial T lymphocytes, and of CD8 ϩ memory-type T cells. 22,23 IL-15 gene is expressed in several tissues, and IL-15 can be either secreted in low amounts or displayed as a membrane-bound cytokine by several cell types. [24][25][26][27][28] Therefore IL-15 is considered a microenvironmental factor, which supports lymphoid cell homeostasis and survival. 29-31 IL-15 is a growth or survival factor not only for CLL cells 13 but also for cells of other lymphoid neoplasias, 32-34 at least in vitro. Moreover, in IL-15-transgenic mice, IL-15 overexpression induces fatal T or NK lymphoproliferative disorders. 35 We and others recently demonstrated that IL-21, the last identified member of the IL-2 family, 36-38 is unable to trigger CLL cell proliferation, but rather induces their apoptosis. 39,40 This effect is potentiated by cell activation with CD40L, 39 with CpG synthetic oligonucleotides, or by BCR cross-linking. 40 IL-21 induces the JAK1 and JAK3 and the STAT1, STAT3, and STAT5 tyrosine phosphorylation in CLL B cells. 39 Similar early signaling events are also activated by IL-21, IL-2, or IL-1...

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Summary. Phenotypic and functional abnormalities within the residual non-B-cell compartment of B-cell chronic lymphocytic leukaemia (CLL) suggest an interaction between tumour cells and host immune effectors. To explore the possibility of a polarized Th1/Th2 response we have studied CD30 antigen expression and the pattern of cytokine production by purified CLL T cells. Activated T cells from CLL patients showed a significant increase in the expression of CD30 compared to normal controls. Accordingly, high levels of soluble CD30 were detected in supernatants from activated T-cell cultures, as well as in CLL serum samples. Messenger RNA for IL4 was found in both resting and, to a greater extent, in activated CLL T lymphocytes. The latter cells were also capable of releasing IL4. Three-colour immunofluorescence analyses revealed a strong CD30 expression in the CD3þ /CD28 ¹ large granular lymphocyte subset, which is considerably expanded in CLL. Production of IL4, as well as expression and release of CD30 by these T cells, was conclusively demonstrated at the clonal level. These findings document an expansion of a peculiar subset of 'Th2-like' cells in CLL, with an increased IL4 production and CD30 expression and release, that are likely to contribute to both the B-cell accumulation and immunedefects characteristic of this disease.

© F e r r a t a S t o r t i F o u n d a t i o nderived from co-culture of monocytes and autologous leukemic cells are characterized by a gene expression profile typical of cells with dysregulated immunocompetence which could be relevant in the context of the acquired immunodeficiency commonly found in CLL patients. 12Whether NLC represent CLL-specific tumor-associated macrophages, as recently suggested, 13 is still debated. We have recently reported that hepatocyte growth factor (HGF), together with CXCL12, is produced at high levels by stromal cells and is capable of prolonging the survival of CLL cells which are positive for the HGF receptor, c-MET.14 HGF is a multifunctional cytokine that induces multiple biological responses in target cells, including adhesion, motility, growth, survival and morphogenesis by activating its tyrosine kinase receptor, c-MET. 15,16 In normal individuals, HGF is constitutively produced by fibroblast-like stromal cells in lymphoid tissue and by follicular dendritic cells within the germinal center microenvironment. 15,17,18 NLC are present in the lymph nodes of CLL patients, where they are interspersed with stromal, dendritic and T cells to form proliferation centers. 19 The intriguing finding that HGF levels are higher in sera from CLL patients than from normal controls, 20 together with a still undefined pattern of effects induced by HGF on myelomonocytic cells, prompted us to determine c-MET expression on NLC and on monocytes-macrophages as well as investigate potential downstream events caused by the interaction between HGF and c-MET. MethodsThis study was approved by the review board of the IRCCS AOU San Martino -IST, Genoa, Italy. Full details are provided in the Online Supplementary Methods file. Cell preparationHeparinized blood or bone marrow samples were taken from CLL patients untreated for at least 3 months. The patients' characteristics are summarized in Online Supplementary Table S1. NLC were derived and characterized as described below and in the Online Supplementary Methods. CD14 + monocytes were purified from patients or healthy donors by magnetic beads. The human monocytic cell line THP-1 was utilized in selected experiments. Fluorescence microscopy and flow cytometryNLC or fresh monocytes from CLL or normal donors were challenged with antibodies against c-MET, indoleamine 2,3-dioxygenase (IDO), vimentin, CD68, interleukin (IL)-10, CD14, CXCR4, CD163 and pSTAT3 TYR705 and analyzed by immunofluorescence or flow cytometry. The quantification of pSTAT3 immunopositive cells area is described in detail in the Online Supplementary Methods. Analysis of STAT3 and pSTAT3 activation by western blottingWestern blotting was used to evaluate STAT3, pSTAT3 and bactin in monocytes from normal or CLL donors and in NLC with or without HGF treatment. Immunohistochemistry and immunofluorescence analysis of lymph node and bone marrow biopsiesTissue sections were probed with anti-human c-MET, -IDO, -vimentin, -CD68, and -CD163. 3,3'-Diaminobenzidine (DAB) substrate chromogen...

An immunotoxin containing an anti-CD30 monoclonal antibody (Ber-H2) and saporin, a ribosome-inactivating protein type 1, is described. It specifically inhibits protein synthesis by Hodgkin derived target cell lines with a very high efficiency (IC50 ranging from 5 x 10(-12) M to 5 x 10(-14) M, as saporin), while irrelevant immunotoxins do not. Present results suggest that this immunotoxin could be used for in vivo therapy as well as for ex vivo bone marrow purging in Hodgkin's disease and CD30+ lymphomas.

The reversal of multidrug resistance by 22 molecules [8-aryl-8-hydroxy-5-R'-8H-[1,4]thiazino[3,4-c][1,2,4]oxadiazol-3-ones (1a-i) and 8-aryl-8-alkoxy-5-methyl-8H-[1,4]thiazino[3,4-c][1,2,4]oxadiazol-3-ones (2a-m)] related to myocardial-calcium-channel-modulator diltiazem was studied in multidrug resistant A2780/DX3 and their sensitive counterpart A2780 cells. MTT, cytofluorimetry assays, and fluorescence microscopy analyses were used to define activity and accumulation of doxorubicin with or without the diltiazem-like modulators. Of the 22 molecules, 1a, 2f, 2g, and 2m were able to overcome the established criteria for the selection in A2780/DX3 cells (IC(50) reduction > or = 25%), but only 2f, 2g, and 2m caused a significant increase of intracellular accumulation of doxorubicin. In conclusion, experiments lead to the identification of three diltiazem-like molecules able to increase the intracellular accumulation of doxorubicin by inhibiting the MDR1 function, thus potentiating its antiproliferative activity in multidrug resistant A2780/DX3 cells.

IL-21, the most recently discovered member of the IL-2 cytokine family, is an attractive subject for research due to its involvement in experimental models of autoimmunity, its ability to down-regulate IgE production, and its anti-tumor properties. Its interest for cancer immunotherapy stems from its physiological immune-enhancing functions. These include regulation of T, B and NK cell proliferation, survival, differentiation, and effector functions. IL-21's functional activities partially overlap those of IL-2. Both cytokines display similar structural features and use the common gamma-chain receptor and its downstream signaling pathways. Besides its activities on normal lymphoid cells, IL-21 is an in vitro growth factor for myeloma and acute-T cell leukemia cells, whereas it induces the apoptosis of B-CLL (chronic lymphocytic leukemia) cells. These findings indicate that the IL-21/IL-21R system exerts opposite functions in different lymphoid neoplasias, and suggest its employment in B-CLL therapy. Since IL-2, but not IL-21, is specifically required for the development of regulatory T (Treg) cell immune-suppressive functions, IL-21 may be a new tool for cancer immunotherapy. It is, in fact, a powerful anti-tumor agent in a variety of murine experimental tumor models through its activation of specific or innate immune responses against neoplastic cells. The preliminary data from phase-I clinical studies suggest that the use of IL-21 is feasible and may result in immune-enhancing effects.