Sensitivity to Interferon-Alpha and Interferon-Stimulated Gene Factor 3 Binding Activity in Human Chronic Myelogenous Leukemia Cell Line KT-1

The mechanism of responsiveness of chronic myelogenous leukemia (CML) cells to interferon (IFN)-(alpha) was examined by using two subclones of CML cell line KT-1 which exhibited significantly different sensitivities to the antiproliferative and apoptosis-inducing effects of IFN(alpha). IFN-stimulated gene factor 3 (ISGF3) formation by IFN-(alpha) was reduced in the IFN-(alpha)-resistant subclone compared to the IFN-(alpha)-sensitive subclone. We conclude that the level of ISGF3 formation is responsible for the difference in IFN-(alpha) responses between these subclones.