Recombinant Human IL-21 Protein

Product information A DNA sequence encoding the extracellular domain of human IL-21 (Q9HBE4-1)) was expressed with the C-terminal fused Fc region of human IgG1. Human CHO cells > 95 % as determined by SDS-PAGE Determined by its ability to stimulate the proliferation of human ANBL-6 cells. The expected ED50 is ≤ 0.5 ng/ml, corresponding to a specific activity of ≥ 2 x10 6  units/mg. < 0.01 EU per μg of the protein as determined by the LAL method. The recombinant human IL-21 consists of 366 amino acids and predicts a molecular mass of 41 Kda. Lyophilized from sterile PBS, pH 7.4. Normally 6 % - 8 % trehalose, mannitol are added as protectants before lyophilization. Samples are stable for up to 24 months from date of receipt at 4 ℃ . Recommend to aliquot the protein into smaller quantities for optimal storage. Avoid repeated freeze-thaw cycles.   Background   IL-21 is a pleiotropic cytokine produced by CD4+ T cells in response to antigenic stimulation. Its action generally enhances antigen-specific responses of immune cells. The biological effects of IL-21 include: inducing the differentiation of T-cell-stimulated B-cells into plasma cells and memory B-cells; the stimulation of IgG production in conjunction with IL-4; and the induction of apoptotic effects in naïve 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. IL-21 exerts its effect through binding to a specific type I cytokine receptor, IL-21R, which also contains the γ chain (γc) found in other cytokine receptors, including IL-2, IL-4, IL-7, IL-9 and IL-15. The IL-21/IL-21R interaction triggers a cascade of events, which includes activation of the tyrosine kinases JAK1 and JAK3, followed by activation of the transcription factors STAT1 and STAT3.