A helical bundle of 4 _-helices, IL2 is an immunoregulatory cytokine that is expressed by CD4+/CD8+ T cells, __ T cells, B cells, eosinophils and dendritic cells. IL2 stimulates growth and differentiation of B-cells, NK cells, lymphokine-activated killer cells, monocytes, macrophages and oligodendrocytes. While Human IL2 shares 56% and 66% amino acid sequence identity with mouse and rat IL2, respectively, only human and mouse IL2 exhibit cross-species activity. Characteristically, IL2 exerts both autocrine and paracrine activity on T cells. In a regulatory role, IL2 is important for the development, survival, and function of regulatory T cells. It enhances Fas-mediated activation-induced cell death, and inhibits the development of inflammatory Th17 cells. Recombinant Human IL2 is expressed in human 293 cells as a monomeric glycoprotein with a molecular mass of 15 kDa.