Human IL-21 is a 4-helix-bundle-type fold cytokine with significant homology to IL-2, IL-4, and IL-15. IL-21 is produced most abundantly by activated CD4⁺ T cells, including Th17 lineage cells and natural killer T (NKT) cells, and has pleiotropic effects on both innate and adaptive immune responses. These actions include positive effects such as enhanced proliferation of NK cells and cytotoxic T cells that can destroy virally infected or cancerous cells and direct inhibitory effects on the antigen-presenting function of dendritic cells. It can also be proapoptotic for B cells and NK cells.

BioLegend’s LEGEND MAX™ Human IL-21 ELISA Kit is a sandwich Enzyme-Linked Immunosorbent Assay (ELISA), in which, a human IL-21 specific monoclonal antibody is pre-coated on a 96-well strip-well plate.
This Human IL-21 ELISA Kit is specifically designed for the accurate quantitation of human IL-21 from cell culture supernatant, serum, plasma, and other bodily fluids. It is ready-to-use, accurate, and sensitive.