IL‑2 in Feline PBMCs. |
IL‑2 was detected in immersion fixed feline peripheral blood mononuclear cells (PBMCs) using Goat Anti-Feline IL‑2 Biotinylated Antigen Affinity-purified Polyclonal Antibody (Catalog # BAF1890) at 10 µg/mL for 3 hours at room temperature. Cells were stained using the NorthernLights™ 557-conjugated Anti-Goat IgG Secondary Antibody (yellow; Catalog # NL001) and counterstained with DAPI (blue). View our protocol for Fluorescent ICC Staining of Non-adherent Cells.
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 δ 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).