Recombinant Mouse IL-2 (Cys160Ser) Protein

Interleukin-2 (IL-2) is an O-glycosylated four alpha-helix bundle cytokine that has potent stimulatory activity for antigen-activated T cells. It is expressed by CD4⁺ and CD8⁺ T cells, gamma delta T cells, B cells, dendritic cells, and eosinophils (1 - 3). Mature mouse IL-2 shares 56% and 73% amino acid (aa) sequence identity with human and rat IL-2, respectively. It shows strain-specific heterogeneity in an N-terminal region that contains a poly-glutamine stretch (4). Mouse and human IL-2 exhibit cross-species activity (5). The receptor for IL-2 consists of three subunits that are present on the cell surface in varying preformed complexes (6 - 8). The 55 kDa IL-2 R alpha is specific for IL-2 and binds with low affinity. The 75 kDa IL-2 R beta, which is also a component of the IL‑15 receptor, binds IL-2 with intermediate affinity. The 64 kDa common gamma chain gammac/IL-2 R gamma, which is shared with the receptors for IL-4, -7, -9, -15, and ‑21, does not independently interact with IL-2. Upon ligand binding, signal transduction is performed by both IL-2 R beta and gammac. IL-2 is best known for its autocrine and paracrine activity on T cells. It drives resting T cells to proliferate and induces IL-2 and IL‑2 R alpha synthesis (1, 2). It contributes to T cell homeostasis by promoting the Fas-induced death of naïve CD4⁺ T cells but not activated CD4⁺ memory lymphocytes (9). IL-2 plays a central role in the expansion and maintenance of regulatory T cells, although it inhibits the development of Th17 polarized cells (10 - 12). Thus, IL-2 may be a key cytokine in the natural suppression of autoimmunity (13, 14).