Human IL21

IL-21 (Interleukin-21) is a potent cytokine regulating many cell types of the immune system, and it is produced by activated T follicular helper cells (Tfh), Th17 cells, and NKT cells. IL-21 protein regulates several aspects of T cell function. In addition to its role in T cell biology, IL-21 also plays a critical role in B cell activation, proliferation, differentiation, and apoptosis. It is also required for the migration of dendritic cells to draining lymph nodes. The 133 amino acid (aa) mature human IL-21 protein shares 63% and 61% aa sequence identity with mouse and rat IL-21 protein, respectively (1-5).