[Different sensitivity of two chronic myeloid leukemia cell lines to interferon-alpha]

The clinical observation has shown that interferon-alpha(IFN-alpha) is one of the most effective therapeutic agents for the malignancies of hemopoietic system and lymphoma. However, IFN-alpha can only induce about 70-80% of the patients with chronic myeloid leukemia (CML) to get hematological remission. The mechanism by which various CML cases respond differently to IFN-alpha is still unclear.

(1)The effects of IFN-alpha in different concentrations (100, 500, 1,000, 5,000, and 10,000 U/ml) on growth of the two CML cell lines were detected by MTT assay,semisolid colony formation and trypan-blue staining for the cells in liquid culture. (2)The cell apoptosis was examined by flow cytometry(FCM),fluorescence microscopy and gel electrophoresis analysis for DNA fragmentation in 48 hours after IFN-alpha (1,000 U/ml) induction of both KT-1/A3 and K562 cells. (3)The expression levels of bcr/abl chimeric genes were analyzed by relative quantitative RT-PCR at 48 hours after cultivation of both KT-1/A3 and K562 cells with IFN-alpha in 1,000 U/ml.

(1)The growth inhibition of KT-1/A3 cells was dose-dependent in IFN-alpha from the concentration of 100 U/ml to 10,000 U/ml. (2)Having been induced with IFN-alpha in 1000 U/ml for 48 hours, the apoptosis rate of KT-1/A3 cells raised from 3.29% to 11.8% and the expression level of bcr/abl chimeric gene in this cell line declined to 66.7% as compared with those of the control. (3)The growth and apoptosis rate as well as bcr/abl gene expression level of K562 cells were not significantly affected by IFN-alpha.

Different populations of CML cells shows different sensitivity to IFN-alpha.