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.