Autocrine cell suicide in a Burkitt lymphoma cell line (Daudi) induced by interferon alpha: involvement of tumor necrosis factor as ligand for the CD95 receptor

The CD95 receptor, a member of the tumor necrosis factor (TNF) receptor sup erfamily, mediates signals for cell death on specific ligand or antibody en gagement. It was hypothesized that interferon alpha (IFN-alpha) induces apo ptosis through activation of the CD95-mediated pathway and that CD95 and li gands of the death domain may belong to the group of IFN-stimulated genes. Therefore, the effect of IFN-alpha on CD95-CD95L expression, on the release of TNF-alpha, and on TNF receptor 1 expression in an IFN-sensitive human B urkitt lymphoma cell line (Daudi) was investigated. After 5 days' incubatio n, apoptosis in 81% of IFN-alpha -treated Daudi cells was preceded by a rel ease of TNF-alpha and an induction of CD95 receptor expression, Although su pernatants of IFN-treated Daudi cells induced apoptosis of CD95-sensitive J urkat cells, CD95L was undetectable on protein or on messenger RNA levels, and the weak initial expression of TNF receptor 1 increased only slightly d uring IFN treatment. Surprisingly, binding of TNF-alpha to CD95 was observe d and confirmed by 3 different techniques-enzyme-linked immunosorbent assay using immobilized CD95: Fc-immunoglobulin G, immunoprecipitation assay usi ng CD95 receptor precipitates of Daudi cells, and binding of sodium iodide 125-TNF-alpha to Daudi cells, which was strongly stimulated by IFN-alpha an d inhibited by CD95L, CD95:Fc, unlabeled TNF-alpha, and anti-TNF-alpha anti body. Preincubation of Daudi cells with antagonists of the CD95-mediated pa thway resulted in an inhibition of IFN-alpha -mediated cell death. The pres ent investigation shows that IFN-alpha induces autocrine cell suicide of Da udi cells by a cross-talk between the CD95 receptor and TNF-alpha. The CD95 receptor can be considered a third TNF receptor, in addition to p55 and p7 5. (Blood.2001;97:2791-2797) (C) 2001 by The American Society of Hematology .