The bioactivity of hIL-28B was determined in a virus protection assay. Hep G2 cells were pre-treated with increasing concentrations of hIL-28B for 24 hours and then inoculated with encephalomyocarditis virus (EMCV) and incubated for an additional 48 hours. Cells were then incubated with a tetrazolium salt and the OD450-OD650 was determined.
The purity of recombinant hIL-28B was determined by SDS-PAGE of 6 µg reduced (+) and non-reduced (-) recombinant hIL-28B and staining overnight with Coomassie Blue.
With carrier: Lyophilized from a 0.22 μm filtered solution of PBS, pH 7.2 containing 20 μg BSA per 1 μg hIL-28B. Carrier free: Lyophilized from a 0.22 μm filtered solution of PBS, pH 7.2.
Stable in lyophilized state at 4°C for 1 year after receipt. Sterile stock solutions reconstituted with carrier protein are stable at 4°C for 2 months and at -20°C for 6 months. Avoid repeated freeze-thaw cycles. Maintain sterility. Storage at -20°C should be in a manual defrost freezer.
>98% as determined by SDS-PAGE of 6 μg reduced (+) and non-reduced (-) recombinant hIL-28B. All lots are greater than 98% pure.
Recombinant hIL-28B contains no "tags" and the nonglycosylated protein has a calculated MW of 19,264. DTT-reduced and non-reduced protein migrate as 21 kDa polypeptides with non-reduced protein having slightly greater mobility due to intramolecular cystines. The expected amino-terminal RLRGA of recombinant hIL-28B was verified by amino acid sequencing.
The bioactivity of recombinant hIL-28B was determined in a virus protection assay. The ED50 of each lot is between 0.4-9 ng/ml.
Less than 0.01 ng endotoxin/1 μg hIL-28B.
Recombinant human IL-28B (hIL-28B) Arg26-Val196 (Accession #NP_742151) was expressed in human 293 cells at Cell Signaling Technology.
IL-28B is a member of the Interferon λ family of cytokines, which includes IL-29 and IL-28A (1). IL-28B is produced by a number of cell types and shares many functions with Type I Interferons (1-3). IL-28B exhibits anti-viral activities in vitro and in vivo (1,2). Investigators have found that IL-28B directly inhibits tumor cell proliferation and promotes anti-tumor immune responses in vivo (1,3). The IL-28 receptor is a heterodimer of the IL-28Rα and IL-10RI (1). IL-28B activates Stat1, Stat3, and Stat5 (1). IL-28Rα expression is limited to a few cell types, including plasmacytoid DC and epithelial cells (1).
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