Interleuking 21
IL-21 is a pro-inflammatory cytokine and is produced by several T cell subsets, including CD4+, T follicular helper and T helper 17 cells. IL-21 is involved in T cell–dependent B cell activation in germinal centers, which leads to rapid proliferation and subsequent differentiation of B cells into memory and long-lived plasma cells. In addition, the IL-21 stimulates proliferation, differentiation and maintenance of CD8 T cells, promotes cytotoxic activity of NK cells and regulates macrophages activation.
Overproduction of IL-21 occurs in many inflammatory diseases such as rheumatoid arthritis, SLE and organ transplantation.