Interferon-γ Receptor β-Chain Expression and Formation of α- and β-Chain Complexes after Receptor Conjugation on Human Peripheral Eosinophils

Background: It has been unclear whether or not the interferon-γ receptor (IFN-γR) on human peripheral eosinophils is completely functional. Accordingly, we examined the expression of IFN-γR α- and β-chains and the association of the two chains after binding of IFN-γ to the receptor. Methods: Peripheral blood eosinophils were obtained from 8 patients (bronchial asthma, n=6, and hypereosinophilic syndrome, n=2), and expression of the α- and β-chain was investigated by flow cytometry with specific antibodies. Expression of mRNA for the α- and β-subunits was also investigated by the reverse transcriptase-polymerase chain reaction. Results: Eosinophils from all the patients were positive for both the α- and β-chains by flow cytometry. In addition, mRNA for both chains was detected by the polymerase chain reaction. Furthermore, coprecipitation of the α- and β-chains was only found after eosinophil stimulation with IFN-γ. Conclusions: Human peripheral eosinophils apparently express both the α- and β-chains of the IFN-γR, and the two chains may only form the receptor complex after ligand binding.