IL-21, human, recombinant
IL-21 is produced by CD4+ T cells in response to antigenic stimulation. IL-21 exerts its effect through binding to a specific type I cytokine receptor, IL-21R, which also contains the gamma chain found in other cytokine receptors including IL-2, IL-4, IL-7, IL-9 and IL-15. Mouse and human IL-21 share 57% amino acid identity.
The IL-21/IL-21 R interaction appears to play important roles in B and T cell proliferation after antigen stimulation and NK cell maturation. It has been shown that IL-21 induces differentiation of T-cells-stimulated B-cells into plasma cells and memory B-cells, stimulates (in conjuction) with IL-4 IgG production, and induces apoptotic effects in naive B-cells and stimulated B-cells in the absence of T-cell signaling. Additionally, IL-21 promotes the anti-tumor activity of CD8+ T-cells and NK cells.
ISOkine™ recombinant human IL-21 is produced in the endosperm tissue of barley grain (Hordeum vulgare), that exhibits up to 50 times less protease activity than E.coli or mammalian cells. Barley seed is void of any human or animal viral contaminants that could jeopardize your cell culture.
Sterile filtered through a 0.2 µm filter. Lyophilized from PBS, pH 7.2
Greater than 95% by SDS-PAGE gel analysis.
Note: Always centrifuge the vial before opening. It is recommended to reconstitute the lyophilized protein in sterile water to a concentration of no less than 100 µg/ml. For long term storage it is recommended to add a carrier protein (0.1% HSA or BSA).
The lyophilized protein, though stable at room temperature for few weeks, is best stored at -20°C. Reconstituted protein should be used immediately or stored in working aliquots at -20°C. Avoid repeated freeze-thaw cycles.
Bioactivity is assayed by measuring the dose dependent effect of ISOkine™ human IL-21 on apoptosis of Mantle cell lymphoma (B cell non-Hodgkin's lymphoma) cells. The ED50 value for this effect is typically = 0.4 ng/ml, corresponding to a specific activity of = 2.5 x 10e6 units/mg. (Ref: Gelebart et al; Leukemia 2009;23; 1836-1846).
Endotoxin level is less than 0.005ng per µg of ISOkine™ product (0.05EU/µg) as measured by turbidimetric kinetic assay.*
Purified ISOkine™ product carries no pyrogenic or pro-inflammatory contaminants, as assayed with monocyte activation test using Human 10-plex Cytokine Assay measuring IL-6, TNF-alpha and IL-1beta induction.**
Recombinant human IL-21 contains 134 amino acids and a 16 a.a. histidine-based tag for a total length of 150 a.a. and has a predicted molecular mass of 17.7 kDa including his-tag. The recombinant protein migrates with an apparent molecular mass of 22 kDa in SDS-PAGE.