Induction of phosphatidylinositol-linked Fcγ receptor III expression on an eosinophilic cell line, EoL-1, by dibutyryl cyclic AMP and interferon-γ

Abstract

The expression of Fcγ receptor III (FcγRIII) on a human eosinophilic leukemia cell line, EoL-1, was examined and compared with its expression on normal blood eosinophils. Surface FcγRIII expression on EoL-1 cells could be induced in vitro with a combination of dibutyryl cAMP (dbcAMP) and gamma-interferon (IFN-γ), but not with IFN-γ or dbcAMP alone. Pretreatment of EoL-1 cells with dbcAMP induced EoL-1 cells to express FcγRIII when stimulated with IFN-γ, but EoL-1 cells pretreated with IFN-γ and then stimulated with dbcAMP failed to express FcγRIII. Cyclic AMP was shown to play a role in the effect of dbcAMP. Both the treatment with phosphatidylinositol-specific phospholipase C (PI-PLC) and the restriction enzyme digestion of FcγRIII cDNA showed that the FcγRIII on EoL-1 cells was a phosphatidylinositol-linked form. On the other hand, freshly isolated blood eosinophils constitutively expressed few, if any, FcγRIII, and IFN-γ induced FcγRIII expression on them in vitro. Dibutyryl cAMP did not induce FcγRIII expression and even suppressed the IFN-γ-induced FcγRIII expression on normal eosinophils. The EoL-1 cell line appears to be a useful in vitro model for the expression and function of the phosphatidylinositol-linked form of FcγRIII on eosinophils.