Human mast cells express both FcεRIα and FcγRIα. IgE up-regulates FcεRIα expression, but IgG1 does not up-regulate FcγRIα expression. The transmembrane domain (TM) of FcγRIα determines the stability of cell surface expression of this receptor.Objective
The aim of this study was to clarify the roles of the TM and cytoplasmic domain (CY) of FcεRIα in IgE-mediated FcεRI up-regulation.Methods
Chimeric receptors created by domain shuffling between FcεRIα and FcγRIα were transduced into human mast cell line HMC-1. Cell surface expression of the chimeric receptors and the effect of IgE or IgG1 on chimeric receptor expression were examined by FACS. The association of the chimeric receptors with FcRγ was investigated by immunoprecipitation.Results
The results showed that the TM and CY of FcεRIα are not essential for IgE-mediated up-regulation of surface FcεRI.Conclusion
The extracellular domain of each Fc receptor determines the diversity of Ig-regulated Fc receptor expression.