Interleukin-4 (IL-4), also known as B cell-stimulatory factor-1, is a monomeric, approximately 13 kDa - 18 kDa 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 α-helix structure.
Specifications and Use of R&D Systems Recombinant Human IL-4
• A DNA sequence encoding the mature IL-4 protein (Yokota, T. et al., 1986, Proc. Natl. Acad. Sci. USA 83:5894) was expressed in E. coli.
Molecular Mass of R&D IL-4
• The methionyl form of the E. coli expressed mature human IL-4 contains 130 amino acid residues and has a molecular mass of approximately 14 kDa.
Purity of R&D IL-4
• > 97%, as determined by SDS-PAGE and visualized by silver stain.
• < 1.0 EU per 1 μg of the cytokine as determined by the LAL method.
Activity of R&D IL-4
• Measured in a cell proliferation assay using a human factor-dependent cell line, TF-1 (Kitamura, T. et al., 1989, J. Cell Physiol. 140:323).
• The ED50 for this effect is typically 0.05 - 0.2 ng/mL.
Formulation of R&D IL-4
• Lyophilized from a 0.2 μm filtered solution in PBS containing 50 μg of bovine serum albumin per 1 μg of cytokine.
• It is recommended that sterile PBS containing at least 0.1% human serum albumin or bovine serum albumin be added to the vial to prepare a stock solution of no less than 10 μg/mL of the cytokine.
Storage of R&D Recombinant IL-4
• Lyophilized samples are stable for up to twelve months from date of receipt at -20° C to -70° C.
• Upon reconstitution, this cytokine can be stored under sterile conditions at 2 - 8° C for one month or at -20° C to -70° C in a manual defrost freezer for three months without detectable loss of activity.
• Avoid repeated freeze-thaw cycles.