Hu Recom IL-4, ACF, 100 µg

STEMCELL Technologies Human Recombinant IL-4 is an animal component-free cytokine also referred to as B cell stimulating factor, BCDF, BCGF, or BSF1. The protein is produced in E. coli, has a predicted molecular mass of 15.1 kDa, and is associated with UniProt accession number P05112. The lyophilized product is prepared from an aqueous solution containing 0.1% trifluoroacetic acid and is sterile-filtered.

Biological activity is determined in a TF-1 cell proliferation assay, with proliferation measured after 72 hours by a fluorometric method. The EC50 is ≤ 0.25 ng/mL, and the specific activity is approximately 1.4 x 10^4 IU/µg, calibrated against the human recombinant IL-4 WHO International Standard (NIBSC code: 88/656). Purity is ≥ 95%, and endotoxin level is ≤ 1 EU/μg protein as measured by kinetic Limulus amebocyte lysate (LAL) analysis. SDS-PAGE analysis under reducing and non-reducing conditions visualizes the protein by Coomassie Blue staining.

IL-4 drives immunoglobulin class switching in B cells (to IgE and IgG4), mast cell hyperplasia, mucus production, and the differentiation of naïve T cells into Th2 cells, which subsequently produce IL-4, IL-5, IL-10, and IL-13. The IL-4 receptor is a heterodimer of IL-4Rα and the common gamma chain; receptor engagement activates JAK1/3 and recruits STAT6 and IRS1/2. IL-4 does not cross-react with mouse cells. For reconstitution, the product should be dissolved in sterile water to at least 0.1 mg/mL by pipetting the solution down the sides of the vial without vortexing. The supplied product is stable for 12 months from the date of receipt.