IL-15 ELISA Kit, Human

BACKGROUND Interleukin-15 (IL-15) is a 14- to 15-kDa member of the 4 alpha-helix bundle family of cytokines. It acts on a wide range of cell types but is most crucial for the development, homeostasis, and function of a specific group of immune cells that includes CD8 T cells, NK cells, NKT cells, and CD8αα intraepithelial lymphocytes. It participates in regulation of both innate and adaptive immunity. IL-15 activates neutrophils and macrophages, promotes the survival of NK cells, and is important for the homeostatic proliferation of CD8⁺ T cells. In vitro, IL-15 appears to be superior to IL-7 in enhancing HIV-specific CD8⁺ T cell effector function and NK-mediated antiviral activity in autologous PBMCs.¹ IL-15 is produced by antigen-presenting cells (APCs) in the early phase of an immune response. It is also present in a broad variety of other tissues and cells such as activated macrophages, keratinocytes, muscle cells, endothelial cells and neural cells. IL-15 expression is controlled at the levels of transcription, translation, and intracellular trafficking. In particular, IL-15 protein is posttranscriptionally regulated by multiple controlling elements that impede translation, including 12 upstream AUGs of the 5' UTR, 2 unusual signal peptides, and the C-terminus of the mature protein.² Abnormalities of IL-15 expression have been described in patients with rheumatoid arthritis or inflammatory bowel disease and in diseases associated with the retroviruses HIV and HTLV-I.³

IL-15 uses two distinct receptor and signaling pathways. In T and NK cells the IL-15 receptor includes IL-2/15R beta and gamma c subunits, which are shared with IL-2, and an IL-15-specific receptor subunit, IL-15R alpha. Mast cells respond to IL-15 with a receptor system that does not share elements with the IL-2 receptor but uses a novel 60- to 65-kDa IL-15RX subunit. In mast cells IL-15 signaling involves Jak2/STAT5 activation rather than the Jak1/Jak3 and STAT5/STAT3 system used in activated T cells. Moreover, as opposed to other cytokines that are secreted, IL-15 primarily exists bound to the high affinity IL-15Ralpha. When IL-15/IL-15Rα complexes are shuttled to the cell surface, they can stimulate opposing cells through the beta/gammaC receptor complex. This novel mechanism of IL-15 delivery has been called trans-presentation.⁴

 

REFERENCES  

1. Budagian, V. et al: Cytokine Growth Factor Rev. 17:259-80, 2006
2. Fehniger, T.A. & Caligiuri, M.A.: Blood. 97:14-32, 2001
3. Perera, L.P.: Arch Immunol Ther Exp (Warsz). 48:457-64, 2000
4. Waldmann, T.A.: Arthritis Res Ther. 6: 174–7, 2004 
 

 

ELISA Kits are based on standard sandwich enzyme-linked immunosorbent assay technology. Freshly prepared standards, samples, and solutions are recommended for best results.