Interleukin-21

Interleukin-21 (IL-21) is a protein and cytokine that plays a crucial role in the immune system. It is produced by T cells, specifically the T follicular helper (Tfh) cells, and has a variety of effects on immune cells.

Structure

IL-21 is a member of the IL-2 family of cytokines. It is a four-α-helix bundle protein, similar in structure to other members of the IL-2 family. The gene encoding IL-21 is located on chromosome 4 in humans.

Function

IL-21 has a broad range of effects on the immune system. It is involved in the differentiation and proliferation of T cells, B cells, natural killer (NK) cells, and dendritic cells. It also promotes the production of antibodies by B cells and enhances the cytotoxic activity of NK cells.

Clinical significance

Due to its role in the immune response, IL-21 has been implicated in a number of autoimmune diseases, including rheumatoid arthritis, systemic lupus erythematosus, and psoriasis. It is also being investigated for its potential use in cancer immunotherapy.

See also

• Interleukin
• Cytokine
• Immune system
• T cell
• B cell
• Natural killer cell
• Dendritic cell