Isolation of Daudi Cells with Reduced Sensitivity to Interferon. IV. Characterization of Clones with Altered Binding of Human Interferon Subspecies

Three clones of Daudi cells, DIF3, DIF8 and DIF9, have been isolated which possess specific interferon (IFN) receptors even though these cells are resistant to both the antiviral and antiproliferative actions of human IFN-alpha. Studies with 125I-labelled cloned human IFN-alpha subspecies showed that clone DIF3 bound IFN in a manner identical to that of the IFN-sensitive parental cells. The initial peak of binding observed 30 min after treatment of either Daudi or DIF3 cells at 37 degrees C with IFN-alpha 2 or IFN-alpha 8 was, however, either absent or much reduced when using DIF8 cells which are resistant to the antiproliferative action of IFN-alpha 2 and -alpha 8. Similarly, no initial peak of binding was observed after treatment of DIF9 cells with IFN-alpha 2 at 37 degrees C. In accord with its reduced biological activity, the binding of 125I-IFN-alpha 1 to either Daudi or DIF8 cells was considerably lower than that of either of the other two IFN-alpha subspecies and followed the form of a hyperbola without an initial transitory peak of binding. It is suggested that the phenotype of IFN resistance of DIF8 and DIF9 cells may be related to a defect in receptor activation whereas the same phenotype of DIF3 cells would appear to be unrelated to IFN binding.