Differential regulation of CD95 (Fas/APO‐1) expression in human blood eosinophils

• Published in: European journal of immunology Vol. 28; no. 7; pp. 2057 - 2065
• Main Authors: Luttmann, Werner, Opfer, Alexander, Dauer, Eva, Foerster, Martin, Matthys, Heinrich, Eibel, Hermann, Schulze‐Osthoff, Klaus, Kroegel, Claus, Virchow, Johann Christian
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY‐VCH Verlag GmbH 01.07.1998
• Subjects: Apoptosis; CD95; Cells, Cultured; Dose-Response Relationship, Drug; Eosinophils - chemistry; Eosinophils - physiology; Fas ligand; Fas Ligand Protein; fas Receptor - analysis; fas Receptor - genetics; fas Receptor - physiology; Granulocyte-Macrophage Colony-Stimulating Factor - pharmacology; Humans; IFN‐γ; Interferon-gamma - pharmacology; Interleukin-3 - pharmacology; Interleukin-5 - pharmacology; Membrane Glycoproteins - physiology; RNA, Messenger - analysis; TNF‐α; Tumor Necrosis Factor-alpha - pharmacology
• ISSN: 0014-2980; 1521-4141
• DOI: 10.1002/(SICI)1521-4141(199807)28:07<2057::AID-IMMU2057>3.0.CO;2-T

CD95 (Fas, APO‐1) is a cell surface receptor expressed on many cells including eosinophils which mediates apoptosis when ligated by agonistic antibodies or its natural ligand FasL. Since inhibition of apoptosis may play an important role in controlling tissue eosinophilia, we investigated the expression of CD95 on purified peripheral blood eosinophils from normal donors. Freshly isolated eosinophils expressed CD95 on the cell surface as well as CD95‐specific mRNA at low levels which did not change during 24‐h culture. Incubation of eosinophils with IL‐3, IL‐5 and granulocyte‐macrophage colony‐stimulating factor (GM‐CSF) did not modulate the basal expression of CD95. IFN‐γ as well as TNF‐α, however, induced a significant, dose‐ and time‐dependent increase in CD95 mRNA and cell surface expression as measured by reverse transcription‐PCR and flow cytometry. Co‐stimulation with IFN‐γ and TNF‐α had synergistic effects on the CD95 surface expression on eosinophils. Addition of IL‐3, IL‐5 or GM‐CSF to IFN‐γ‐ and TNF‐α‐stimulated eosinophils caused in a reduction of CD95 expression. Functional activity for CD95 following incubation with IFN‐γ and TNF‐α was demonstrated by increased apoptosis in response to cross‐linking with FasL. From these data, we conclude that IFN‐γ and TNF‐α can up‐regulate cell surface expression of CD95 on eosinophils, which leads to an increased susceptibility of eosinophils to Fas‐mediated apoptosis. Thus, our results suggest that receptors involved in eosinophil apoptosis can be regulated by antagonistic cytokines.