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-1beta, tumor necrosis factor-alpha, and interferon-gamma 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-gamma 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-y induced apoptosis in acute leukemia via NO and caspase 3 pathway.