IL-4

Alias: Interleukin-4, B-cell stimulatory factor 1

IL-4 is a TH2 anti-inflammatory cytokine that is secreted by activated TH2 and NKT cells, and to a lesser extent by TH1 and mast cells. IL-4 exerts numerous effects on various hematopoietic cell types by biding to either type I or Type II IL-4R (the latter of which IL-13 also binds to and as such is also referred to as IL-13R). IL-4, by the means of STAT6 and GATA3, promotes TH2 cell differentiation that produces IL-4, IL-5, and IL-13. In B cells, IL-4 promotes proliferation and differentiation, promotes immunological class switching to IgE and IgG1 isotypes (in conjunction with other signals such as CD40), and upregulates MHC class II and CD23 expression. In T and B lymphocytes, mast cells, and endothelial cells, IL-4 promotes survival, growth, and differentiation. In macrophages, IL-4 can inhibit the production of TNF, IL-1, and IL-6. With its relevance to disease, IL-4 is an immune-stimulating molecule. As such it is one of the more recent targets being studied for new asthma treatments.