Changes in Binding of Alpha Interferon IFN-αA to HL-60 Cells During Myeloid Differentiation

Abstract

The differentiation of human leukemic HL-60 cells from their predominantly promyelocyte form to a neutrophil-like state can be induced by the addition of dimethylsulfoxide (DMSO) or retinoic acid (RA) to the growth medium. The binding of human recombinant interferon IFN-αA to the undifferentiated and differentiated HL-60 cells was investigated. Within 2 days after the addition of DMSO or retinoic acid to growing HL-60 cells, the binding of IFN-αA to treated cells increases significantly relative to its binding to untreated cells. The difference in binding of IFN-αA between the treated and untreated cells continues to increase for at least 3 days. Analysis of binding curves of IFN-αA to neutrophil-like and promyelocytic HL-60 cells leads to the conclusion that the increased binding of [¹²⁵I]IFN-αA to neutrophil-like cells is primarily the result of an increase in the number of binding sites on these cells.