No abstract

Chronic myeloid leukaemia (CML) is a myeloproliferative disorder characterized by the presence of Philadelphia chromosome and by BCR-ABL1, which encodes the BCR-ABL oncoprotein. Although imatinib mesylate (IM) is effective for CML treatment, patients in accelerated and blastic phases of the disease are often refractory to this therapy, and there are also cases of IM resistance in patients in the chronic phase. Therefore, potential new drugs are being investigated to improve the efficiency of the therapy of CML such as snake venoms and their compounds. In this investigation, Bothrops pirajai L-amino acid oxidase (BpirLAAO-I) effect on normal peripheral blood mononuclear cells (PBMC) and on BCR-ABL + cell line was assessed to explore its potential against leukaemic cells. MTT viability assay, lymphocyte subsets quantification and cell activation markers expression were performed to evaluate BpirLAAO-I effect on normal PBMC. The effect of BpirLAAO-I on HL-60 and HL-60.BCR-ABL cell lines was assessed by apoptosis detection. BpirLAAO-I was able to induce apoptosis in HL-60 and HL-60.BCR-ABL cell lines in a dose-dependent manner, promoted caspases 3, 8 and 9 activation and enhanced IM effect while not affecting the viability of normal cells. In addition, BpirLAAO-I promoted immune cells activation and lymphocytes subsets changes on normal PBMC. The results indicate that BpirLAAO-I induces apoptosis and potentiates IM effect on BCR-ABL + cells.Chronic myeloid leukaemia (CML) is a myeloproliferative disorder characterized by the presence of Philadelphia chromosome (Ph) and by BCR-ABL1 neogene, which encodes BCR-ABL oncoprotein. BCR-ABL presents a constitutive tyrosine kinase (TK) activity which is responsible for the resistance of BCR-ABL-positive cells to apoptosis and CML pathogenesis [1][2][3]. Apoptosis could be triggered by intrinsic (also referred to mitochondrial) and extrinsic pathways. The intrinsic pathway is related to release of cytochrome c from mitochondria followed by caspase-9 and caspase-3 activation [4,5], while extrinsic pathway involves death receptors stimulation followed by caspase-8 and caspase-3 triggering without direct involvement of mitochondria [5][6][7]. Studies showed that BCR-ABL expression in myeloid cells contributes to block intrinsic and extrinsic apoptosis pathways [8,9]. Chronic myeloid leukaemia treatments are chemotherapy (hydroxycarbamide), interferon-a and therapies that modulate antileukaemic immune response such as allogeneic bone marrow transplantation and donor lymphocyte infusion [10,11] and tyrosine kinase inhibitors (TKIs). In 2001, the TKI imatinib mesylate (IM) revolutionized CML treatment, becoming the standard first-line therapy [12]. Imatinib mesylate presents high activity in patients with CML at chronic phase inducing over 95% of complete haematological response and 73% of complete cytogenetic remission [13]. Imatinib mesylate therapy is effective, but imatinib-resistant cell clones have already been described and patients treated in disease advanced phase...

A DNA vaccine expressing dengue-4 virus premembrane (prM) and envelope (E) genes was produced by inserting these genes into a mammalian expression plasmid (pCI). Following a thorough screening, including confirmation of protein expression in vitro, a recombinant clone expressing these genes was selected and used to immunize BALB/c mice. After 3 immunizations all the animals produced detectable levels of neutralizing antibodies against dengue-4 virus. The cytokines levels and T cell proliferation, detected ex vivo from the spleen of the immunized mice, showed that our construction induced substantial immune stimulation after three doses. Even though the antibody levels, induced by our DNA vaccine, were lower than those obtained in mice immunized with dengue-4 virus the levels of protection were high with this vaccine. This observation is further supported by the fact that 80% of the vaccine immunized group was protected against lethal challenge. In conclusion, we developed a DNA vaccine employing the genes of the prM and E proteins from dengue-4 virus that protects mice against this virus.

Treatment with interferon-alpha is effective for chronic myelogenous leukemia in the chronic phase (CML-CP), but the immunological mechanisms of the antileukemic effect of this substance are still unclear. The objective of this study was to investigate the immunological effects of interferon-alpha in CML patients. Markers of cellular activation and apoptosis, natural killer (NK) cell cytotoxicity and production of intracellular cytokines (IFN-gamma, IL-2 and IL-4) were determined by flow cytometry in the peripheral blood mononuclear cells (PBMC) of 26 CML-CP patients before and 3, 6 and 9 months after IFN-alpha treatment. The results were correlated with the hematological response. In the whole group of patients, INF-alpha use was followed by a significant increase of lymphocytes producing IL-2 and IFN-gamma, an increase in NK activity and a decrease in the number of CD34+ cells. Out of 26 CML patients, 15 achieved hematological remission and 7 achieved partial cytogenetic remission after 9 months of IFN-alpha treatment. There was an increase in the percentage of CD8/FasL+, DR/CD3+, DQ/CD3+, CD34/Fas+, DR/CD56+, CD56/FasL+ cells and of IFN-gamma- and IL-2-producing lymphocytes and an increase in NK cytotoxicity only in the group of patients who achieved complete hematological remission. Our results indicate that IFN-alpha use in CML-CP reduces the number of CD34+ cells, activates T cells, enhances stem cell apoptotic markers and increases the production of intracellular IFN-gamma and IL-2 by lymphocytes. Taken together, these results indicate that the therapeutic effect of IFN-alpha in CML-CP is mediated at least in part by immunological mechanisms.