Description
Interleukin-4 (IL-4) is a pleiotropic cytokine that regulates diverse T and B cell responses including differentiation of naive T cells into the TH2 phenotype, promoting B cell proliferation, antibody isotype switching, and expression of other TH2 cytokines including IL-5 and IL-9. IL-4 plays a critical role in the development of allergic inflammation and asthma.It enhances both secretion and cell surface expression of IgE and IgG1. It also regulates the expression of the low affinity Fc receptor for IgE (CD23) on both lymphocytes and monocytes. IL-4 is produced primarily by activated CD4+ T-lymphocytes, NK 1.1+ T-cells (NKT), mast cells and basophils.One major role of IL-4 is priming the differentiation of precursor CD4+ T-cells into Th2 effector cells by altering their cytokine expression during activation.IL-4 has also been shown to have other stimulatory effects on B-cells including increased expression of CD23, IL-4R, IgM and MHC class II molecules on their surface