Ultra-LEAF™ Purified anti-human IL-4 Recombinant, IL-4, QA20A30,BioLegend,945303

IL-4 is the primary cytokine implicated in the development of Th2-mediated responses, which is associated with allergy and asthma. IL-4 binds to two receptor complexes, the Type I receptor comprises IL-4Rα and the common gamma-chain (γc), which is also shared by the cytokines IL-2, -7, -9, -15 and -21 and is present in hematopoietic cells. IL-4 can use the type II complex, comprising IL-4Rα and IL-13Rα1, which is present in non-hematopoietic cells. This second receptor complex is a functional receptor for IL-13, which shares approximately 25% homology with IL-4. The type I receptor complex can be formed only by IL-4 and is active in Th2 development. In contrast, the type II receptor complex formed by either IL-4 or IL-13 is more active during airway hypersensitivity and mucus secretion and is not found in T cells. IL-4, through its activation of STAT6, upregulates GATA3 expression and also suppresses TH1 and TH17 cell responses, partly through the upregulation of growth factor independent 1(GFI1), a transcriptional repressor of IFN-γ and IL-17 production. IL-4 induces macrophage activation and TSLP production. IL-4 recruits and activates IgE-producing B cells (IgE class switching) and enhances IgE-mediated responses by up-regulating IgE receptors on B lymphocytes, mast cells, and basophils. In addition, IL-4 also induces VCAM-1 on vascular endothelium and thus directs the migration of T lymphocytes, monocytes, basophils, and eosinophils to the inflammation site.