6-Methoxyluteolin from Chrysanthemum zawadskii var. latilobum suppresses histamine release and calcium influx via down-regulation of FcεRI α chain expression.

Mast cells and basophils are important effector cells in immunoglobulin-E (IgE)-mediated allergic reactions. Using the human basophilic KU812F cells, we assessed the inhibitory effects of 6-methoxyluteolin, isolated from Chrysanthemum zawadskii, in the FcεRI-mediated allergic reaction. We determined that 6-methoxyluteolin inhibited anti-FcεRI α chain antibody (CRA-1)-induced histamine release, as well as elevation of intracellular calcium concentration [Ca2+]i in a dose-dependent manner. Moreover, the inhibitory effects of 6-methoxyluteolin on the cell surface expression and the mRNA level of the FcεRI α chain were determined by flow cytometric analysis and reverse transcription-polymerase chain reaction (RTPCR), respectively. Therefore, these results show that 6- methoxyluteolin is a potent inhibitor of histamine release and calcium influx via down-regulation of the FcεRI α chain.