MONOMERIC HUMAN IGE EVOKES A TRANSIENT CALCIUM RISE IN INDIVIDUAL HUMAN NEUTROPHILS

Digital fluorescence calcium imaging was used to investigate and ident ify the primary biological responses of human neutrophils to monomeric immunoglobulin E (IgE). Treatment of neutrophils with IgE caused a tr ansient rise in the level of intracellular calcium that was inhibited by pertussis toxin. The calcium rise was due mainly to release from an intracellular membrane-enclosed store that is also sensitive to the c hemotactic peptide formyl-Met-Leu-Phe. The IgE-induced calcium transie nt was independent of Fc gamma receptors and of Fc epsilon receptor li gation. Our data suggest that the mere binding of IgE to neutrophils i s sufficient to evoke a biological response without the need for IgE/r eceptor cross-linking.