Co-aggregation of FcγRII with FcεRI on human mast cells inhibits antigen-induced secretion and involves SHIP-Grb2-Dok complexes

Abstract

Signaling through the high affinity IgE receptor FcεRI on human basophils and rodent mast cells is decreased by co-aggregating these receptors to the low affinity IgG receptor FcγRII. We used a recently described fusion protein, GE2, which is composed of key portions of the human γl and the human ε heavy chains, to dissect the mechanisms that lead to human mast cell and basophil inhibition through co-aggregation of FcγRII and FcεRI. Unstimulated human mast cells derived from umbilical cord blood express the immunoreceptor tyrosine-based inhibitory motif-containing receptor FcγRII but not FcγRI or FcγRIII. Interaction of the mast cells with GE2 alone did not cause degranulation. Co-aggregatin..