Identification of the FceRI-activated tyrosine kinases Lyn, Syk, and Zap-70 in human basophils

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
Christopher Kepley, Associate Professor (Creator)
The University of North Carolina at Greensboro (UNCG )
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Abstract: Background: In human blood basophils, cross-linking the high-affinity IgEreceptor FceRI with multivalent antigen activates a signaling pathway leading to Ca2+ mobilization, actin polymerization, shape changes, secretion, and cytokine production. Methods and Results: The role of tyrosine kinases in human FceRI signaling was explored by using human basophils isolated by Percoll gradient centrifugation followed by negative and/or positive selection with antibody-coated magnetic beads. FceRI cross-linking of more than 95% pure basophil preparations activates the protein-tyrosine kinases Lyn and Syk, previously linked to FceRI-coupled rodent mast cell activation, as well as Zap-70, previously implicated in T-cell receptor signaling, and causes the tyrosine phosphorylation of multiple proteins. The presence of Lyn, Syk, and Zap-70 in basophils was confirmed by Western blotting in lysates of highly purified basophils and independently by confocal fluorescence microscopy in cells labeled simultaneously with kinase-specific antibodies and with the basophil-specific antibody 2D7. Comparable amounts of Lyn and Syk were found in basophils and B cells, whereas T cells appear to have greater amounts of Zap-70 than basophils. The tyrosine kinase inhibitor piceatannol spares IgE-mediated Lyn activation but inhibits IgE-induced Syk and Zap-70 activation as well as overall protein tyrosine phosphorylation and secretion. Overall protein-tyrosine phosphorylation increases steadily over a range of anti-IgE concentrations that are low to optimal for secretion. However, tyrosine phosphorylation continues to increase at high anti-IgE concentrations that elicit very little secretion (the characteristic high-dose inhibition of secretion). Conclusions: Our data demonstrate the association of anti-IgE–stimulated, protein-tyrosine phosphorylation by a cascade of tyrosine kinases, including Zap-70 as well as Lyn and Syk, with the initiation of FceRI-mediated signaling in human basophils.

Additional Information

Journal of Allergy and Clinical Immunology 1998; 102(2):304-15.
Language: English
Date: 1998
IgE receptor, IgE, basophils, allergy, signal transduction, tyrosine kinases

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