Mast cells (MC) , a major participant in inflammation and allergy, can initiate an early defense response to foreign invaders. Besides expressing high-affinity IgE receptor, MC also expresse a large number of G protein-coupled receptors (GPCRs) . Various studies have shown that cationic micromolecules represented by substance P and many peptidergic drugs can induce MC degranulation through a novel receptor, Mas-related G protein-coupled receptor X2 (MrgprX2) . MrgprX2 plays an important role in allergy, itching and pseudo-allergic drug reactions. It will help explain some clinical difficulties which can not be explained by classical IgE-dependent activation of MC, and provides potential therapeutic targets for MC-mediated diseases.

Mast cells; Immunoglobulin E; Receptors, G-protein-coupled; Pruritus