The B7-CD28 family of costimulatory molecules modulate T cell receptor signals and play essential roles in the control of T cell-mediated immune responses. CD28, the most extensively studied co-signaling receptor, accepts a co-stimulatory signal from B7-1 (CD80) or B7-2 (CD86, B70) and promotes activation of naive T cells in the presence of a T cell receptor signal, On the other hand, CTLA-4, a CD28 homolog expressed on activated T cells, serves as a checkpoint to attenuate T cell responses upon ligation of B7-1 and/or B7-2. Inducible Co-stimulator (ICOS), another CD28 homolog in the same gene cluster with CD28 and CTLA4, is expressed on activated T cells and co-stimulates T cell activation upon binding of a distinct ligand CD275 (B7-H2). Recent data demonstrated that CD275, best known as the ligand of Inducible Co-stimulator, was also a ligand for CD28 and CTLA-4 in human, Similar to B7-1 and B7-2, CD275 co-stimulation via CD28 induced survival factor Bcl-xL, downregulated cell cycle inhibitor p27kip1 and triggered signaling cascade of ERK and AKT kinases-dependent pathways. Understanding this pathway is very important in the development of therapeutic interventions against human diseases.

Full-length recombinant human CD275 extracellular domain cDNA (19 - 256 aa, derived from BC064637) was constructed with codon optimization and expressed with a small T7-His-TEV cleavage site Tag (29aa) fusion at its N-terminal and expressed in E.coli as inclusion bodies. The final product was refolded using our unique “temperature shift inclusion body refolding” technology and chromatographically purified.

1. May be used for in vitro human T cell-mediated immune responses or lymphoid differentiation regulation study coating with this protein.

2. May be used for protein-protein interaction assay.

3. As antigen for specific antibody production.