Changes in binding of alpha interferon IFN-alpha A to HL-60 cells during myeloid differentiation

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-alpha A 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-alpha A to treated cells increases significantly relative to its binding to untreated cells. The difference in binding of IFN-alpha A between the treated and untreated cells continues to increase for at least 3 days. Analysis of binding curves of IFN-alpha A to neutrophil-like and promyelocytic HL-60 cells leads to the conclusion that the increased binding of [125I]IFN-alpha A to neutrophil-like cells is primarily the result of an increase in the number of binding sites on these cells.