Flavones suppress type I IL-4 receptor signaling by down-regulating the expression of common gamma chain.

Immunoglobulin E (IgE) production is induced by interleukin (IL)-4 signaling mediated by type I IL-4 receptor (IL-4R) in B cells. We found that flavones inhibited IL-4-induced epsilon germline transcription which is essential for IgE class switching, and the phosphorylation of signal transducer and activator of transcription 6, janus kinase 3, and IL-4Ralpha, whereas IL-4 signaling mediated through type II IL-4R was unaffected by flavones. Furthermore, flavones reduced the expression of common gamma chain, a characteristic constituent subunit of type I IL-4R, suggesting that flavones suppress type I IL-4R signaling.