IL-4 plays a strong immuno-modulatory role. Produced primarily by activated T-cells, mast cells, and basophils, it important anti-inflammatory; as well as a regulator of antibody isotype wsitching to IgE production and differentiation of T-cells into TH2 cells.

IL-4 is a 154 amino acid protein with biological activity similar to IL-13. The IL-4 receptor is a heterodimer of the bunding subunit and the gamma chain which is also shared by IL-2, IL-7, IL-9 and IL-15 receptors. There is both a membrane bound and a soluble form of the receptor. Membrane bound IL-4 receptor has also been shown to complex with IL-13 receptor to improve the affinity of the IL-13 receptor.

IL-4 is one of the key anti-inflammatory mediators. Not usually found in high levels naturally, it’s effects are potent. It is often assayed in many different types of research because of its far-reaching effects, including inflammation, TH0 differentiation, and humoral immunity. The cytokines assayed with depends on the type of experiment, but include, IL-2, IL-6, IL-7, IL-9, IL-10, IL-12, IL-15, IFNy, GM-CSF and TNFa.