Recombinant Human IL-4 (His, Strep)

Interleukin-4 (IL-4), also known as B cell-stimulating factor-1, is a secreted protein that belongs to the IL-4/IL-13 family. It is a glycosylated peptide containing three intrachain disulfide bonds and adopting a bundled structure of four α-helix. Mature human IL-4 has amino acid sequence identity of 55%, 39%, and 43% with bovine, mouse, and rat IL-4, respectively. The activity of IL-4 in human, mouse, and rat is species-specific. IL-4 exerts its effects through two receptor complexes. Type I receptors expressed on hematopoietic cells are heterodimers of ligand-bound IL-4 Rα and co-γ chains (shared subunits of IL-2, -7, -9, -15, and -21 receptors). Type II receptors on non-hematopoietic cells are composed of IL-4 Rα and IL-13 Rα1. Type II receptors also transduce IL-13-mediated signaling. IL-4 is predominantly expressed by Th2-biased CD4+ T cells, mast cells, basophils, and eosinophils. It promotes cell proliferation, survival, and conversion of immunoglobulin-like classes to IgG4 and IgE in human B cells, Th2 phenotype acquisition by naïve CD4+ T cells, initiation and chemotaxis of mast cells, eosinophils, and basophils, and proliferation and activation of epithelial cells.