A type 1 membrane glycoprotein belonging to the immunoglobulin superfamily, cluster of differentiation 200 (CD200) binds the CD200 receptor (CD200R) that is expressed on the surface of myeloid cells and T cells (Wright et al.), and has been shown to inhibit myeloid cell activity and macrophage cytokine production (Jenmalm et al.). Homologues of CD200 have been identified in viruses and can interact with CD200R to reduce macrophage pro-inflammatory cytokine production (Foster-Cuevas et al.). Studies have shown that the immunosuppressive effects of CD200 can promote acceptance of allogeneic tissue grafts in hosts (Gorczynski et al.), whereas dysregulation of CD200/CD200R can contribute to the development of autoimmune conditions, such as rheumatoid arthritis (Ren et al.). CD200 contains two immunoglobulin-like domains, a V-type domain and a smaller C2-type domain (Hatherley et al.). This protein contains a His-residue tag at the carboxyl end of the polypeptide chain. For consistency and reproducibility across your applications, cluster of differentiation 200 from STEMCELL comes lyophilized with ≥ 95% purity, and is verified by LAL analysis to ensure endotoxin levels are ≤ 1.0 EU/μg protein. Human recombinant CD200 at 2 μg/mL can bind human CD200R (His & hFc tag) with a linear range of 5 - 28 ng/mL, as determined by functional ELISA.