Membrane IgE binds and activates Fc epsilon RI in an antigen-independent manner.
Interaction of secretory IgE with FcepsilonRI is the prerequisite for allergen-driven cellular responses, fundamental events in immediate and chronic allergic manifestations. Previous studies reported the binding of soluble FcepsilonRIalpha to membrane IgE exposed on B cells. In this study, the functional interaction between human membrane IgE and human FcepsilonRI is presented. Four different IgE versions were expressed in mouse B cell lines, namely: a truncation at the Cepsilon2-Cepsilon3 junction of membrane IgE isoform long, membrane IgE isoform long (without Igalpha/Igbeta BCR accessory proteins), and both epsilonBCRs (containing membrane IgE isoforms short and long). All membrane IgE versions activated a rat basophilic leukemia cell line transfected with human FcepsilonRI, as detected by measuring the release of both preformed and newly synthesized mediators. The interaction led also to Ca(2+) responses in the basophil cell line, while membrane IgE-FcepsilonRI complexes were detected by immunoprecipitation. FcepsilonRI activation by membrane IgE occurs in an Ag-independent manner. Noteworthily, human peripheral blood basophils and monocytes also were activated upon contact with cells bearing membrane IgE. In humans, the presence of FcepsilonRI in several cellular entities suggests a possible membrane IgE-FcepsilonRI-driven cell-cell dialogue, with likely implications for IgE homeostasis in physiology and pathology.
Vangelista
Luca
L
Department of Biology and Genetics, University of Milan, Milan, Italy. vangelista.luca@hsr.it
Soprana
Elisa
E
Cesco-Gaspere
Michela
M
Mandiola
Paola
P
Di Lullo
Giulia
G
Fucci
Rita N
RN
Codazzi
Franca
F
Palini
Alessio
A
Paganelli
Giovanni
G
Burrone
Oscar R
OR
Siccardi
Antonio G
AG
D000818:Animals; D000941:Antigens / Q000502:physiology*; D016175:B-Lymphocyte Subsets / Q000276:immunology / Q000378:metabolism; D001491:Basophils / Q000276:immunology / Q000378:metabolism; D001666:Binding Sites, Antibody; D001667:Binding, Competitive / Q000276:immunology; D016466:CHO Cells; D002118:Calcium / Q000378:metabolism; D002450:Cell Communication / Q000276:immunology; D002452:Cell Count; D045744:Cell Line, Tumor; D006224:Cricetinae; D006801:Humans; D007073:Immunoglobulin E / Q000378:metabolism* / Q000502:physiology; D051379:Mice; D009000:Monocytes / Q000276:immunology / Q000378:metabolism; D046912:Multiprotein Complexes / Q000378:metabolism; D011485:Protein Binding / Q000276:immunology; D020033:Protein Isoforms / Q000096:biosynthesis / Q000378:metabolism; D051381:Rats; D011947:Receptors, Antigen, B-Cell / Q000378:metabolism* / Q000502:physiology; D017455:Receptors, IgE / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000378:metabolism*; D013189:SRS-A / Q000031:analogs & derivatives / Q000378:metabolism; D012995:Solubility; D013997:Time Factors
D000941:Antigens; D046912:Multiprotein Complexes; D020033:Protein Isoforms; D011947:Receptors, Antigen, B-Cell; D017455:Receptors, IgE; D013189:SRS-A; D007073:Immunoglobulin E; D002118:Calcium