Module 11: Figure mast cell inhibitory signalling
Inhibition of mast cell release by FcγRIII and β2-adrenoceptors.
Release of inflammatory mediators by mast cells is inhibited by FcγRIII and β2-adrenoceptors. The former bind IgE and are drawn into the FcεRI complex, where they are phosphorylated by Lyn and this enables them to bind the phosphatases Src homology 2 (SH2) domain-containing inositol 5-phosphatase (SHIP) and SH2 domain-containing protein tyrosine phosphatase-1 (SHP-1) that can dephosphorylate the lipid messenger PtdIns3,4,5P3 and phosphorylated proteins respectively. The β2-adrenoceptors produce cyclic AMP that appears to inhibit the Ca2+ signalling pathway.