As a major event in type ?? allergic reaction,degranulation of mast cells is triggered by the interaction between specific IgEs and high affinity IgE receptors (Fc??RIs) on mast cell membrane,and is followed by the release of a battery of inflammatory mediators,such as histamine,leukotrienes and arachidonic acid,and these inflammatory mediators in turn induce a series of allergic symptoms.Recently,Allergin-1 has been found to be an immunoglobulin-like receptor preferentially expressed on mast cells.The crosslinking of Allergin-1 to Fc??RIs on mast cells may inhibit the signal transduction from Fc??RIs to intracellular immunoreceptor tyrosine-based inhibitory motif (ITIM),generate ITIM inhibitory signals,which then participate in the regulation of mast cell degranulation,and finally block the initiation of allergic inflammation.