Integrin α_IIbβ₃ induces the adhesion and activation of mast cells through interaction with fibrinogen

Integrin α_IIb, a well-known marker of megakaryocyte- platelet lineage, has been recently recognized on hemopoietic progenitors. We now demonstrate that integrin α_IIbβ₃ is highly expressed on mouse and human mast cells including mouse bone marrow-derived mast cells, peritoneal mast cells, and human cord blood-derived mast cells, and that its binding to extracellular matrix proteins leads to enhancement of biological functions of mast cells in concert with various stimuli. With exposure to various stimuli, including cross-linking of FcεcRI and stem cell factor, mast cells adhered to extracellular matrix proteins such as fibrinogen and von Willebrand factor in an integrin α_IIbβ₃- dependent manner. In addition, the binding of mast cells to fibrinogen enhanced proliferation, cytokine production, and migration and induced uptake of soluble fibrinogen in response to stem cell factor stimulation, implicating integrin α_IIbβ₃ in a variety of mast cell functions. In conclusion, mouse and human mast cells express functional integrin α_IIbβ₃.