MRGPRX2 drives non-IgE mast cell activation and anaphylaxis, fundamentally shifting hypersensitivity paradigm.

The classical IgE-mediated paradigm often falls short in explaining many severe anaphylaxis and mast cell-driven reactions. This gap limits precise diagnosis and targeted therapies for non-IgE hypersensitivity. The Mas-related G protein-coupled receptor X2 (MRGPRX2) has emerged as a pivotal mediator in these non-IgE pathways, offering a new conceptual framework for mast cell activation. Its involvement in adverse reactions to common drugs like protamine, antibiotics, and neuromuscular blocking agents underscores its critical clinical relevance, highlighting an urgent need to understand these alternative mechanisms.

This comprehensive review synthesized recent findings on MRGPRX2's multifaceted role in non-IgE-mediated mast cell activation and anaphylaxis. The authors examined structural and signaling insights, clinical implications, and therapeutic potential by integrating data from numerous studies. The review highlighted MRGPRX2 as a key receptor for rapid mast cell degranulation in response to a broad spectrum of cationic ligands, including drugs, neuropeptides, and host defense peptides. It also elucidated the receptor's dual coupling to both Gi and Gq signaling pathways.