Studies with a monoclonal antibody to the β subunit of the receptor with high affinity for immunoglobulin E

Abstract

The receptor with high affinity for IgE consists of a tetrameric complex of polypeptides, one of which (α), contains the binding site for IgE. The function of the other chains—a single and two disulfide-linked γ chains—is unknown. We report the cloning of a murine hybridoma that secretes an IgG1 antibody which specifically reacts with the subunit. Studies with this monoclonal antibody show that the subunit stoichiometry of the receptor is unaffected by the presence or absence of bound IgE. We also found that under certain conditions where the αβγ₂ complex dissociates, remains attached to the dimer of γ chains, indicating that these chains contact each other in the native receptor. In rat basophilic leukemia cells—a neoplastic line of mucosal-type mast cells—all of the subunits expressed by the cells appeared to be associated with the high affinity receptor. However, in at least one cell line which has no high affinity receptors—a putative rat lymphoma line—β or β-like polypeptides were also expressed.