B7-1/CD80 Long Isoform Extracellular Domain (human, recombinant; His- and Fc-tagged)

CD80, also known as B7-1, is a glycoprotein and member of the CD28/B7 family of co-stimulatory receptors that promotes T cell activation.^1,2 Alternative splicing of CD80 produces one full-length long isoform, CD80 long, and two short isoform, s1CD80 and s2CD80.² CD80 long exists as a membrane-bound dimer and is composed of an extracellular immunoglobulin variable (IgV) domain that interacts with the co-stimulatory molecule CD28 or the inhibitory molecule CTLA-4, as well as an immunoglobulin constant (IgC) domain and a cytoplasmic tail that are both required for T cell co-stimulation.¹ s1CD80 and s2CD80 lack the transmembrane domain or the transmembrane domain and the IgC domain, respectively, and are found in the serum.² CD80 is transiently expressed on the surface of antigen-presenting cells (APCs) and is upregulated following ligation of the co-stimulatory molecule CD86, as well as by pro-inflammatory stimuli, such as LPS, and downregulated by the anti-inflammatory cytokine IL-10.^3,4,5 CD80 has two ligands, CD28 and CTLA-4, that compete for binding and are each expressed on naïve T cells but have opposing functions on T cell activation.⁶ CD80 binding to CD28 promotes T cell activation, survival, and cytokine production, whereas CD80 binding to CTLA-4 inhibits T cell activation and promotes T cell anergy. Neutralization of CD80 with a monoclonal antibody reduces the severity of synovitis and bone erosion, as well as CD4⁺ T cell infiltration, in inflamed joints in a mouse model of arthritis induced by complete Freund's adjuvant (CFA) and BSA.⁷ Decreased CD80 tumor levels have been identified in patients with renal cell carcinoma.⁸ CD80 SNPs have been found in individuals with gastric cancer.⁹ Cayman's B7-1/CD80 Long Isoform Extracellular Domain (human, recombinant; His- and FC-tagged) protein can be used for ELISA applications. This protein is a disulfide-linked homodimer. The reduced monomer, comprised of B7-1/CD80 (amino acids 35-242) fused to His-tagged human IgG1 Fc at its C-terminus, consists of 455 amino acids, a calculated molecular weight of 51.7 kDa, and a predicted N-terminus of Val35 after signal peptide cleavage. As a result of glycosylation, the monomer migrates at approximately 80-90 kDa by SDS-PAGE under reducing conditions.

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1. Girard, T., Gaucher, D., El-Far, M., et al. CD80 and CD86 IgC domains are important for quaternary structure, receptor binding and co-signaling function. Immunol. Lett. 161(1), 65-75 (2014).

2. Kakoulidou, M., Giscombe, R., Zhao, X., et al. Human soluble CD80 is generated by alternative splicing, and recombinant soluble CD80 binds to CD28 and CD152 influencing T-cell activation. Scand. J. Immunol. 66(5), 529-537 (2007).

3. Mir, M.A. Costimulation in lymphomas and cancers. Developing costimulatory molecules for immunotherapy of diseases 185-254 (2015).

4. Sahoo, N.C., Rao, K.V.S., and Natarajan, K. CD80 expression is induced on activated B cells following stimulation by CD86. Scand. J. Immunol. 55(6), 577-584 (2002).

5. Zhou, F., Ciric, B., Li, H., et al. IL-10 deficiency blocks the ability of LPS to regulate expression of tolerance-related molecules on dendritic cells. Eur. J. Immunol. 42(6), 1449-1458 (2012).

6. Buchbinder, E.I., and Desai, A. CTLA-4 and PD-1 pathways: Similarities, differences, and implications of their inhibition. Am. J. Clin. Oncol. 39(1), 98-106 (2016).

7. Odobasic, D., Leech, M.T., Xue, J.R., et al. Distinct in vivo roles of CD80 and CD86 in the effector T-cell responses inducing antigen-induced arthritis. Immunology 124(4), 503-513 (2008).

8. Flörcken, A., Johannsen, M., Nguyen-Hoai, T., et al. Immunomodulatory molecules in renal cell cancer: CD80 and CD86 are expressed on tumor cells. Int. J. Clin. Exp. Pathol. 10(2), 1443-1454 (2017).

9. Wu, R., Li, F., Zhu, J., et al. A functional variant at miR-132-3p, miR-212-3p, and miR-361-5p binding site in CD80 gene alters susceptibility to gastric cancer in a Chinese Han population. Med. Oncol. 31(8), 60 (2014).