Revealed at last: Structure of the antibody-receptor complex common to all IgE-mediated allergic hypersensitivity reactions.

Immunoglobulin E (IgE) binds with high affinity to its receptor, FcεRI, on mast cells and basophils, and cross-linking of allergen-specific IgE by minute amounts of multivalent allergen stimulates a powerful and immediate allergic reaction. In this issue of , Zhang report the three-dimensional structures of the human and murine receptors, with and without bound IgE-Fc, to reveal some intriguing differences between mouse and human in this critical antibody-receptor interaction.