Published online before print September 10, 2008
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RI on human plateletsDivision of Clinical Immunology and Rheumatology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
2 Correspondence: Division of Clinical Immunology and Rheumatology, Department of Medicine, University of Alabama at Birmingham, 202 Shelby Interdisciplinary Biomedical Science Building, 1825 University Boulevard, Birmingham, AL 35294-2182, USA. E-mail: jmwu{at}uab.edu
Fc
RI (CD89) is a human IgA FcR expressed on cells of myeloid lineage such as neutrophils, monocytes, tissue macrophages, eosinophils, and subpopulations of dendritic cells. Fc
RI mediates cell activation through Src family kinases and downstream tyrosine-based phosphorylation pathways. However, the role of IgA and the expression and role of its cognate receptor Fc
RI (CD89) in platelet activation are undefined. In the current study, we demonstrate that human platelets express Fc
RI mRNAs and proteins. Furthermore, we show that the platelet Fc
RI is associated with the FcR
-chain, and cross-linking of Fc
RI leads to Syk phosphorylation. Clustering of Fc
RI induces pre-mRNA splicing and protein production of tissue factor and IL-1β, suggesting novel roles for human platelet Fc
RI and serum IgA in thrombosis and inflammation.
Key Words: CD89 pre-mRNA splicing IL-1_oblique>β tissue factor