CONCANAVALIN-A INDUCED HISTAMINE-RELEASE FROM HUMAN BASOPHILS INVITRO

Abstract

The site of interaction for concanavalin A (Con-A)-induced histamine release from human basophils was studied in vitro. Blocking the .epsilon.-determinant (D .fwdarw. 1) of Ig[immunoglobulin]E with high concentrations of monomer (Fab) anti-D.epsilon.1 does not significantly inhibit the quantity of histamine released by suboptimum concentrations of Fc specific anti-IgE. The monomer anti-D.epsilon.1 apparently does not have the capacity to sterically hinder the bridging of all of the determinants in the C.epsilon.3 and C.epsilon.4 domains (Fc''-.epsilon.''region) of IgE. The monomer anti-D.epsilon.1 does effectively inhibit release induced by suboptimum concentrations of Con-A. For suboptimum concentrations, Con-A activation is IgE mediated and takes place in the proximity of D.epsilon.1 and not at the membrane receptor for IgE.