ABSTRACT
Background: Leukemia is characterized by the uncontrolled accumulation of white blood cells. Recently, cytokines have been used in immunotherapy, which is a new strategy for leukemia treatment. Objective: To investigate the effect of cytokines on induction of apoptosis in acute leukemic cell lines; HL-60, MV4-11, K-562 and Molt-4 and in addition, to study the involvement of nitric oxide (NO) in apoptotic pathways. Methods: Leukemic cell lines were incubated with cytokines; interleukin-1β, tumor necrosis factor-a, and interferon-γ in various concentrations and for variable periods of time. The percent apoptosis and caspase 3 activation were examined by flow cytometry. Moreover, NO production and inducible nitric oxide synthase (iNOS) mRNA were measured by using Griess method and Real-time PCR, respectively. Results: Cytokines caused a time and dose-dependent induction of apoptosis in leukemic cell lines. The highest cell apoptosis was found in K-562 treated with 40 U/ml interferon-γ for 48 hours; this correlated with the result of cell growth inhibition and caspase 3 activation. NO and iNOS mRNA were increased in cytokines treated cells. Moreover, apoptosis was reduced by SMT, an iNOS inhibitor, which confirms the possible involvement of NO in the apoptotic pathway. Conclusion: Cytokines especially interferon-g induced apoptosis in acute leukemia via NO and caspase 3 pathway.
ABSTRACT
In order to study the role of the cytokine interleukin-3 (IL-3) and its signaling pathways in erythropoiesis of beta-thalassemia/HbE erythroid progenitor cells, CD34 positive cells were isolated from peripheral blood of patients and healthy subjects. After culturing the cells in the presence or absence of IL-3, cell viability was measured by trypan blue staining and apoptotic cells were analyzed by flow cytometry. After 7 days of culture the highest percent erythroid progenitor cell viability was obtained with cells from healthy subjects, while the lowest percentage was found in those from splenectomized beta-thalassemia/HbE. Viability of beta-thalassemia/HbE erythroid progenitor cells in the presence of IL-3 was higher than that of nonsupplemented cells. In addition, specific inhibitors of protein kinase C (Ro-318220), phospholipase C (U-73122) and Janus kinase 2 (AG-490) were used to investigate the involvement of signaling pathways in erythropoiesis. Percent apoptosis of erythroid progenitor cells from splenectomized beta-thalassemia/HbE subjects treated with RO-318220 was higher than those of nonsplenectomized beta-thalassemia/HbE and healthy subjects. Treatment with U-73122 resulted in enhanced percent apoptotic cells from normal and beta-thalassemia/HbE subjects. All these effects were independent of IL-3 treatment.