Description
Interleukin 2 (IL-2) is produced by activated T cells. IL-2 was first described as a T cell growth factor. It is now known to stimulate growth and differentiation of B cells, natural killer (NK) cells, lymphocyte activated killer (LAK) cells, monocytes/macrophages and oligodendrocytes. Mouse IL-2 is species- specific and is inactive on human cells. The biological activity of IL-2 is mediated by the binding to a cell surface receptor. The functional high-affinity receptor of IL-2 is composed of three distinct polypeptide chains, the IL-2 receptor a, b and g subunits. The intermediate-affinity IL-2 receptor complex, which lacks the a subunit, but contains both the b and g subunits, is also capable of transducing the IL-2 signal. The g chain of the IL-2 receptor complex has been shown to be a subunit of the receptor complexes of IL-4, IL-7, IL-9 and IL-15. Biological activity of IL-2 is mediated by JAK1 and JAK3-induced activation of STAT3 and STAT5. Recombinant mouse IL-2, containing a mixture of the 149 amino acid residue protein and the 150 amino acid residue N-methionyl form, has a predicted molecular mass of approximately 17.2 kDa