Treatment of lymphoblastoid cells with interferon decreases insulin binding

Lymphoblastoid Daudi cells, which are highly sensitive to growth inhibition by interferon (IFN), can be grown in a defined serum-free medium containing insulin, transferrin, and albumin as the only proteins. We examined whether the growth inhibition by IFN could be in part due to a change in receptors for insulin or transferrin. Cells treated for at least 2 days with 100 units/ml of IFN-alpha 2 bound less 125I-insulin and after 3 days of treatment this binding was reduced by more than 50%. No change in the binding of 125I-transferrin was observed. Treatment with IFN of Raji cells, which are resistant to growth inhibition by IFN, resulted in a similar decrease in 125I-insulin binding. Growth inhibition of Daudi cells by serum deprivation had no effect on 125I-insulin binding. Therefore, the IFN-induced loss of insulin binding sites is not a consequence of growth inhibition.