Descriptopn：Interleukin 4 （IL-4） is a cytokine that that functions as a potent regulator of immunity.
It is secreted primarily by mast cells, Th2 cells, eosinophils, and basophils.
IL-4 signals through the IL-4R α-chain which activates several pathways.
This activation can lead to B cell proliferation, survival of T and B cells and chemokine production.
IL-4 has been shown to have a role in allergic asthma through its regulation of TH2 cell proliferation and IgE synthesis, and atopy or excessive IgE production has been associated with elevated levels of IL-4 in response to allergens.
