Interleukin 2 (IL-2) is a pleiotropic cytokine produced primarily by mitogen- or antigen-activated T lymphocytes (1, 2). It plays a key role in promoting the clonal expansion of antigen-specific T cells. In addition, IL-2 has been shown to mediate multiple immune responses on a variety of cell types.

IL-2 has been found to stimulate growth and differentiation of B cells, NK cells, LAK cells, monocytes, and oligodendocytes. IL-2 is involved in treatment of cancers such as melanoma and renal cell cancer. It plays a key role in promoting the clonal expansion of antigen-specific T cells. In addition, IL-2 has also been shown to mediate multiple immune responses on a variety of cell types.

The sequence of rat IL-2 cDNA predicts a 155 amino acid (aa) residue precursor glycoprotein containing a 20 aa residue signal peptide that is cleaved to form the mature protein (3). At the amino acid sequence level, mature rat IL-2 is approximately 80% identical to mouse IL-2 (1-4).

The biological effects of IL-2 are mediated by specific cell surface receptor complexes. The functional high-affinity receptor for IL-2 is composed of three distinct polypeptide chains(5, 6).

IL-2 stimulates the proliferation of thymocytes; stimulates the proliferation and differentiation of activated B cells; promotes the growth, differentiation and cytocidal activity of monocytes; induces the growth of and cytokine production and cytolytic activity by natural killer cells; enhances the production of lymphocyte-activated killer (LAK) cells; and induces the proliferation and differentiation of oligodendrocytes (1, 2).