Concanavalin A induced histamine release from human basophils in vitro.
The site of interaction for concanavalin A (Con-A)-induced histamine release from human basophils was studied in vitro. Blocking the epsilon one determinant (D leads to 1) of IgE with high concentrations of monomer (Fab) anti-Depsilon1 does not significantly inhibit the quantity of histamine released by suboptimum concentrations of Fc specific anti-IgE. This indicates that the monomer anti-Depsilon1 does not have the capacity to sterically hinder the bridging of all of the determinants in the Cepsilon3 and Cepsilon4 domains (Fc'-epsilon-region) of IgE. The monomer anti-Depsilon1 does effectively inhibit release induced by suboptimum concentrations of Con-A. The data indicate that for suboptimum concentrations, Con-A activation is IgE mediated and takes place in the proximity of Depsilon1 and not at the membrane receptor for IgE.
D001491:Basophils / Q000276:immunology*; D001666:Binding Sites, Antibody; D003176:Complement C3; D003181:Complement C4; D003208:Concanavalin A / Q000494:pharmacology*; D004306:Dose-Response Relationship, Immunologic; D000939:Epitopes; D006636:Histamine Release / Q000187:drug effects*; D006801:Humans; D007073:Immunoglobulin E; D007141:Immunoglobulin Fc Fragments; D066298:In Vitro Techniques
D003176:Complement C3; D003181:Complement C4; D000939:Epitopes; D007141:Immunoglobulin Fc Fragments; D003208:Concanavalin A; D007073:Immunoglobulin E