Ecklonia cava extract suppresses the high-affinity IgE receptor, FcεRI expression

Basophils and mast cells express Fc epsilon RI, a high-affinity receptor for IgE, on the cell surface and act as effector cells in allergic reactions. In this study, we investigated the inhibitory effect of Ecklonia cava (EC) methanolic extract on the expression of Fc epsilon RI in human basophilic KU812F cells, Flow cytometric analysis revealed that EC extract caused a concentration-dependent reduction in the cell surface expression of Fc epsilon RI. The extract was also capable of reducing the binding between IgE or serum IgE and cell surface Fc epsilon RI. RT-PCR analysis revealed that EC extract reduced the mRNA expression of total cellular Fc epsilon RI alpha-chain. Moreover, data obtained by fluorescence spectrophotometry showed that the extract inhibited the Fc epsilon RI-mediated release of histamine in a concentration-dependent manner. These results suggest that EC extract may exert its anti-allergic activity through negative-regulation of Fc epsilon RI expression and a decrease in histamine release. (C) 2009 Elsevier Ltd. All rights reserved.