ICOS/CD278 Extracellular Domain (human, recombinant)

Inducible T cell co-stimulator (ICOS) is a glycoprotein and member of the CD28/B7 family of co-stimulatory receptors that promotes T cell activation.¹ It exists as a membrane-bound disulfide-linked homodimer and contains a leader peptide, an extracellular domain that interacts with ICOS ligand (ICOSL), and a cytoplasmic tail that mediates association with PI3K and is critical for T cell activation.^1,2 ICOS is expressed on activated CD4⁺ and CD8⁺ T cells following T cell receptor crosslinking and/or co-stimulation by CD28.¹ ICOS co-stimulation of T cells induces production of IL-4, IL-5, IL-6, IFN-γ (Item Nos. 32008 | 32078), TNF-α (Item Nos. 32020 | 32069), and GM-CSF (Item Nos. 32044 | 32079), but not IL-2, and superinduces production of IL-10, as well as prevents T cell apoptosis.² Human melanoma cells express ICOSL and promote the expansion of ICOS⁺ IL-10-secreting regulatory T cells, which is positively correlated with unfavorable clinical outcomes.³ Administration of an anti-ICOS monoclonal antibody ameliorates mucosal inflammation and damage in a mouse model of T helper cell-induced chronic colitis.⁴ Cayman's ICOS/CD278 Extracellular Domain (human, recombinant) protein can be used for ELISA. This protein is a disulfide-linked homodimer. The reduced monomer, comprised of ICOS (amino acids 21-141) fused to His-tagged human IgG1 Fc at its C-terminus, consists of 386 amino acids, has a calculated molecular weight of 41.6 kDa, and a predicted N-terminus of Glu21 after signal peptide cleavage. As a result of glycosylation, the monomer migrates at approximately 50 kDa by SDS-PAGE under reducing conditions.

WARNING This product is not for human or veterinary use.

1. Wikenheiser, D.J., and Stumhofer, J.S. ICOS Co-Stimulation: Friend or Foe? Front. Immunol. 7, 304 (2016).

2. Beier, K.C., Hutloff, A., Dittrich, A.M., et al. Induction, binding specificity and function of human ICOS. Eur. J. Immunol. 30(12), 3707-3717 (2000).

3. Amatore, F., Gorvel, L., and Olive, D. Inducible co-stimulator (ICOS) as a potential therapeutic target for anti-cancer therapy. Expert Opin. Ther. Targets 22(4), 343-351 (2018).

4. Kanai, T., Totsuka, T., Tezuka, K., et al. ICOS costimulation in inflammatory bowel disease. J. Gastroenterol. 37(Suppl 14), 78-81 (2002).