title: Molecular characterization of the low-affinity IgE receptor Fc epsilonRII/CD23 expressed by human eosinophils.
abstract: CD23/Fc epsilonRII, the low-affinity receptor for IgE, is a pluripotent molecule with pleiotropic effects on cell activation and proliferation, antigen presentation and IgE synthesis. Initial investigations have suggested that CD23 expression was restricted to B lymphocytes and macrophages, but a much wider cell distribution is now acknowledged. Despite experimental evidence suggesting that human eosinophils could express the low-affinity IgE receptor Fc epsilonRII/CD23 with biological functions, no molecular cloning data have been reported until now. Whereas in situ hybridization confirmed the expression of CD23 mRNA in eosinophils, RT-PCR analysis of human eosinophil cDNA derived from a cDNA library revealed the presence of CD23, totally homologous with the CD23 a and b sequences. Eosinophils from different hypereosinophilic patients as well as the eosinophilic leukemia cell line EoL-3, analyzed by RT-PCR, expressed both CD23 a and b isoforms. In situ RT-PCR confirmed that mRNA corresponding to CD23 a and b isoforms was detected in human eosinophils. Finally, immunocytochemistry allowed us to show a differential expression of Fc epsilonRII/CD23 and Fc epsilonRI by subpopulations of eosinophils, with a preferential expression of Fc epsilonRII/CD23 in the hypodense population. These results provide definitive evidence that the low-affinity IgE receptor (Fc epsilonRII) synthesized by human eosinophils is identical to the CD23 molecule expressed on B cells, and that the two CD23 isoforms a and b can be expressed by eosinophils.
authors.affiliation: INSERM U167, Institut Pasteur, Lille, France.
authors.forename: S G
authors.initials: SG
authors.lastname: Abdelilah
authors.forename: L
authors.initials: L
authors.lastname: Bouchaïb
authors.forename: M
authors.initials: M
authors.lastname: Morita
authors.forename: A
authors.initials: A
authors.lastname: Delphine
authors.forename: S
authors.initials: S
authors.lastname: Marika
authors.forename: C
authors.initials: C
authors.lastname: André
authors.forename: C
authors.initials: C
authors.lastname: Monique
mesh_terms: D001483:Base Sequence; D003001:Cloning, Molecular; D004804:Eosinophils / Q000378:metabolism / Q000648:ultrastructure*; D005091:Exons; D006801:Humans; D007073:Immunoglobulin E / Q000378:metabolism; D017403:In Situ Hybridization; D007536:Isomerism; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017455:Receptors, IgE / Q000097:blood* / Q000737:chemistry / Q000235:genetics*; D014158:Transcription, Genetic
chemical_list: D012333:RNA, Messenger; D017455:Receptors, IgE; D007073:Immunoglobulin E