Biolegend, 798806, Biotinylated Recombinant Human ICOS-Fc Chimera (carrier-free), 100μg

Inducible costimulatory molecule (ICOS) is a member of CD28 superfamily protein. It has unique roles in T cell activation and differentiation, splenic germinal center formation, and immunoglobulin class switching. The expression of ICOS within the first 48 hours after T cell activation suggests that it may contribute to the differentiation of T cells during the primary response. ICOS binds to its ligand B7H, which is constitutively expressed at low levels on the surface of APCs and is upregulated by TNF-α or lipopolysaccharide. It was demonstrated that ICOS-B7H2 interaction plays an important role in the generation of CD4+ and CD8+ Tregs, and mediates the suppressive functions of CD4+ Tregs by regulating CTLA-4 expression on cell surfaces induced by allogeneic CD40-activated B cells. In the ICOS-KO mice, the T cell-mediated isotype switching is impaired while the IFN-gamma response is slightly affected; in addition, the ICOS-negative T cells do not accumulate in B cell follicles. Also, secondary, but not primary, clonal proliferation of antigen-specific B cells is impaired in ICOS-KO mice, and therefore the generation of secondary antibody-secreting cells is also impaired. These results suggest that this protein plays a pivotal role in T cell activation and Th1/Th2 differentiation. Mouse and human B7-H2 exhibit cross species binding to ICOS. B7-H2 interaction costimulates T cell proliferation, development of B cells, plasma cells, follicular helper T cells, and germinal centers. In addition, human B7-H2 binds to CD28 and CTLA4. The interaction of human B7-H2 and CD28 can costimulate both human mouse naïve T cells and regulatory T cells (Treg). B7-H2 plays a role in the development of allergic asthma by enhancing Th2 biased immune responses, limiting Th17 responses, and promoting eosinophilic infiltration into the lungs. B7-H2 activation of ICOS on Tregs limits pulmonary inflammation and airway hyper-responsiveness, promotes the development of inhalational tolerance, and impairs anti-tumor immunity.
100μg
Source: Human ICOS, amino acid (Glu21-Phe141) (Accession # Q9Y6W8.1), with a linker (GS), a C-terminal human IgG1 (Pro100-Lys330) and an Avi-tag, was expressed in CHO cells. Human ICOS-Avi tag was site-specifically biotinylated by enzyme BirA.
Molecular Mass: The 369 amino acid recombinant protein has a predicted molecular mass of approximately 41.64 kD. The DTT-reduced and non-reduced protein migrates at approximately 60 kD and 110-240 kD by SDS-PAGE, respectively. The predicted N-terminal amino acid is Glu.
Purity: > 95%, as determined by Coomassie stained SDS-PAGE.
Formulation: 0.22 µm filtered protein solution is in PBS, 5% glycerol.
Endotoxin Level: Less than 0.1 EU per µg cytokine as determined by the LAL method.
Concentration: 25 µg size is bottled at 200 µg/mL. 100 µg size and larger sizes are lot-specific and bottled at the concentration indicated on the vial. To obtain lot-specific concentration and expiration, please enter the lot number in our Certificate of Analysis online tool.
Storage & Handling: Unopened vial can be stored between 2°C and 8°C for up to 2 weeks, at -20°C for up to six months, or at -70°C or colder until the expiration date. For maximum results, quick spin vial prior to opening. The protein can be aliquoted and stored at -20°C or colder. Stock solutions can also be prepared at 50 - 100 µg/mL in appropriate sterile buffer, carrier protein such as 0.2 - 1% BSA or HSA can be added when preparing the stock solution. Aliquots can be stored between 2°C and 8°C for up to one week and stored at -20°C or colder for up to 3 months. Avoid repeated freeze/thaw cycles.
Activity: Biotinylated recombinant human ICOS-Fc binds to immobilized human B7-H2 (ICOSL) in a dose dependent manner. HRP Avidin (Cat. No. 405103) was used to detect the binding. The ED50 for this effect is 3 - 18 ng/mL.
Application: Bioassay
Application Notes: BioLegend carrier-free recombinant proteins provided in liquid format are shipped on blue-ice. Our comparison testing data indicates that when handled and stored as recommended, the liquid format has equal or better stability and shelf-life compared to commercially available lyophilized proteins after reconstitution. Our liquid proteins are validated in-house to maintain activity after shipping on blue ice and are backed by our 100% satisfaction guarantee. If you have any concerns, contact us at [email protected].
Structure: Disulfide-bond linked homodimer
Distribution: Activated T cells
Function: ICOS regulates the production of IL-4 and IL-10, immunoglobulin-isotype class switching, the formation of germinal centers, and regulation of T cell proliferation. ICOS expression is influenced by TCR and CD28 signals. CD28 costimulation enhances ICOS expression, and ICOS upregulation is markedly reduced in the absence of B7-1 and B7-2.
Interaction: Antigen presenting cells, epithelial cells , and tumor cells
Ligand/Receptor: B7-H2 (ISCOL, CD275)
Bioactivity: Measured by its ability to bind recombinant human B7-H2 (ICOSL)
Cell Type: B cells, Dendritic cells, Tregs
Biology Area: Cell Adhesion, Cell Biology, Costimulatory Molecules, Immunology, Signal Transduction
Molecular Family: Immune Checkpoint Receptors, Soluble Receptors, TCRs
Antigen References: Arimura Y, et al. 2002. Int Immunol. 14:555-66. Mahajan S, et al. 2007. Eur J Immunol. 37:1796-808. Harada H, et al. 2003. J Clin Invest. 112:234-43. Dong C, et al. 2001. Nature. 409:97-101. McAdam AJ, et al. 2001. Nature. 409:102-5.
Gene ID: 28951
UniProt: View information about ICOS on UniProt.org
Regulatory Status: RUO
Other Names: Inducible costimulator, AILIM (activation inducible lymphocyte immunomediatory molecule) and CRP 1 (CD28 related protein 1), CD278, CVID1, H4