Interleukin-4 (IL-4), also known as B cell-stimulatory factor-1, is a monomeric, ~13kD-18kD Th2 cytokine that shows pleiotropic effects during immune responses. It is a glycosylated polypeptide that contains three intrachain disulfide bridges and adopts a bundled four a-helix structure. Rabbit IL-4 is synthesized with a 24aa signal sequence. Mature rabbit IL-4 shares 47%, 56%, 39% and 40% aa sequence identity with bovine, human, mouse, and rat IL-4, respectively. Human, mouse, and rat IL-4 are species-specific in their activities. IL-4 exerts its effects through two receptor complexes. The type I receptor, which is expressed on hematopoietic cells, is a heterodimer of the ligand binding IL-4 Ra and the common G chain (a shared subunit of the receptors for IL-2, -7, -9, -15, and -21). The type II receptor on nonhematopoietic cells consists of IL-4 Ra and IL-13 Ra1. The type II receptor also transduces IL-13 mediated signals. IL-4 is primarily expressed by Th2-biased CD4+ T cells, mast cells, basophils, and eosinophils. It promotes cell proliferation, survival, and immunoglobulin class switch to IgG4 and IgE in human B cells, acquisition of the Th2 phenotype by nai?ve CD4+ T cells, priming and chemotaxis of mast cells, eosinophils, and basophils, and the proliferation and activation of epithelial cells. IL-4 plays a dominant role in the development of allergic inflammation and asthma.
Recombinant corresponding to aa25-147 from rabbit IL-4, fused to N-terminal Met, expressed in E.coli.
Measured in a cell proliferation assay using TF-1 human erythroleukemic cells. Kitamura, T. et al. (1989) J. Cell Physiol. 140:323.The ED50 for this effect is typically 3-15ng/ml.
Endotoxin: ~1EU/1ug (LAL)
Storage and Stability:
Lyophilized powder may be stored at -20 degrees C. Stable for 12 months at -20 degrees C. Reconstitute with sterile buffer. Aliquot to avoid repeated freezing and thawing. Store at -20 degrees C. Reconstituted product is stable for 3 months at -20 degrees C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.