Interleukin-2 (IL-2) is a small
monomeric protein 133
amino acids in length. It is a very important
cytokine in the
immune response. It is secreted by
T-lymphocytes and helps signal the body to produce more
T-helper cells. It also controls
B-cells,
T-cytotoxic cells ,
natural killer cells and
lymphokine activated killer cells.
The tertiary structure of protein is a four-helix bundle. It interacts with the IL-2 receptor, which sits on the cell surface of T-cells and transmits a signal into the cells which then promote proliferation.