A tea catechin suppresses the expression of the high-affinity IgE receptor FcεRI in human basophilic KU812 cells

Human basophilic KU812 cells express the high-affinity IgE receptor Fc is an element of RI, which plays a central role in the IgE-mediated allergic response. The effect of several major tea catechins, (+)-catechin, (-)-epicatechin, (-)-epigallocatechin, (-)-epicatechin gallate, and (-)-epigallocatechin gallate (EGCg), on the cell surface expression of Fc is an element of RI in KU812 cells was studied. Flow cytometric analysis showed that only EGCg was able to decrease the cell surface expression of Fc is an element of RI after a 24 h treatment in a dose-dependent manner. Moreover, immunoblot analysis revealed that the total cellular expression of the Fc is an element of RI alpha chain decreased upon treatment with EGCg. Fc is an element of RI is a tetrameric structure comprising one alpha chain, one beta chain, and two gamma chains. The level of mRNA production of each subunit in KU812 cells was investigated. KU812 cells treated with EGCg expressed lower levels of Fc is an element of RI alpha and gamma mRNA than nontreated cells. These results suggest that EGCg has an ability to down-regulate Fc is an element of RI expression, and this suppressive effect may be due to the down-regulation of Fc is an element of RI alpha and gamma mRNA levels.