Recombinant Feline IL-2 (Cys146Ser) Protein

Interleukin-2 (IL-2) is a secreted, single chain alpha‑helical polypeptide that has potent stimulatory activity for antigen-activated T cells. The feline IL-2 gene encodes a 154 amino acid (aa) precursor protein with a 20 aa signal peptide plus a 134 aa mature segment. There are suggestions that the mature protein may be O-glycosylated. At the aa sequence level, mature feline IL-2 is 78%, 82%, 60%, 64%, 62%, 75%, 62%, and 76% identical to mature human, canine, mouse, rat, cotton rat, porcine, goat, and equine IL-2, respectively. Mammalian cells known to express IL-2 include CD4⁺ and CD8⁺ T cells, visceral smooth muscle cells, eosinophils, gamma delta T cells, B cells and dendritic cells. The biological activity of IL-2 is mediated by IL-2 receptor complexes consisting of three distinct subunits ( alpha, beta, gamma) in two combinations. The high‑affinity signaling IL-2 receptor complex is a heterotrimer of the IL-2 receptor alpha, beta, gamma subunits. The intermediate signaling complex is a heterodimer of the IL-2 R beta and gamma subunits. The non-ligand binding   gamma subunit, referred to as the common gamma subunit ( gamma_c), is also a subunit of the receptor complexes of IL-4, IL-7, IL-9 and IL-15. Functionally, IL-2 is best known for its autocrine and paracrine activity on T cells. On naïve CD8⁺ T cells, high IL-2 levels can induce cell proliferation with a bias towards cytotoxicity. In the presence of low levels of IL-2, CD8⁺ T cells preferentially undergo apoptosis with a bias towards cytokine secretion. IL-2 also seems to play a central role in the expansion and maintenance of CD4⁺ CD25⁺ regulatory T cells. This indicates IL-2 may be a key cytokine in the natural suppression of autoimmunity (1 - 9).